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Description: The Weather Shield is an easy to use Arduino shield that grants you access to barometric pressure, relative humidity, luminosity and temperature. There are also connections on this shield to optional sensors such as wind speed, direction, rain gauge and GPS for location and super accurate timing.

These Weather Shields utilize the HTU21D humidity, MPL3115A2 barometric pressure, and ALS-PT19 light sensors and relies on the HTU21D and MPL3115A2 Arduino libraries. Each shield comes with two unpopulated RJ11 connector spaces (for optional hook up of rain and wind sensors) and a 6-pin GPS connector (for optional hook up of a GP635T GPS module). Finally, each Weather Shield can operate from 3.3V up to 16V and has built in voltage regulators and signal translators.

Note: The Weather Shield comes as a stand-alone board. Headers, connectors, and additional sensors will need to be purchased separately, check the related items or wish list below!


  • Humidity/Temperature Sensor - HTU21D
  • Barometric Pressure - MPL3115A2
  • Light Sensor - ALS-PT19


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Customer Comments

  • Folks, I wonder if someone has used this shield with the Intel Edison board. I connected this shield to the Edison and the the 2 IC2 addresses (0x40 & 0x60) are not recognised by the board. The same shield work quite well with the UNO and MEGA boards. I want to build a robust weather information server and this shield could fit quite well if I am make it to work. Thanks. AC/.

    BTW: The shield works perfectly with the Arduino Galileo, so it is not related to the hardware architecture

  • I am about done with my weather station. I added Xbee Wifi, Sparkfun Data, RTC and most importantly, support for the AS3935 lightning sensor located here: which Joe rewrote to use Wire.h

    Next weeks build should include 6) UV sensor added (I2C) 7) Cloud sensor (this is a tad experimental but it uses non-contact temperaure measures to read the cloud )I2C

    • Quick question - where did you get your AS3935 lightning sensor from? I’ve been looking but always seem to find one that’s too expensive or sold out :/

    • dude wanna ask if ur using all the said devices in its wishlist?… cause im planning to use arduino that directs it to pc rather than wifi

    • Does your station use the rain and win meters as well?

      If so, how did you get this to work, since XBee shield wants the same pins (2,3) as they use?

    • If it’s the same UV sensor I’ll be using, it’s not I2C…

    • I have spent the last two days on that exact set up and I cannot figure out what I’m doing wrong. I have the weather shield and the XBee shield and I can either get the weather stuff to work (displaying on the serial console) or the wifi to work (sending some dummy data to Sparkfun Data) but it I try to get them both working it seems like the communication with the XBee gets trashed. The hardware in all cases remains the same (Arduino + XBee + Weather) - all I am doing is changing the sketch. I even have a version of s sketch that has the XBee working and all I have to do is just include wire.h and it break; don’t even do anything with it just add that one line and the communication dies. Would love to see how you’ve managed to do this…any hints would be appreciated!

      • my email is - if you send me an email, i will send you the code tomorrow when I get home. I presume you have softwareserial for the xbee. I had all sorts of problems with memory. I had to put the program on big diet to get down to a spot it would run.

        But drop me a note and tomorrow I’ll send you the code.


        • Many thanks for helping me get past my issues with this shield. I was using this in conjunction with the XBee WiFi along with, essentially, the sample code from the weather shield hookup guide and the Internet Datalogging with XBee WiFi guide. And while this all makes complete sense and each is a great resource on their own it tends to put a little stress on the memory of an Uno R3. Once we trimmed the fat on memory usage (specifically RAM usage) the stack has been running great!

          One last note…I found that stacking the two shields (Uno then XBee then Weather - if you put Weather before XBee the light sensor is kinda pointless) causes the temperature sensor to give higher than actual readings. Its amazing how much heat the XBee gives off. I “solved” this by simply moving the XBee to an Explorer Regulated breakout.

  • My temperature will only show up as “tempf=-1766.2”. The humidity is working however. Anyone know what could be the issue here? Any help would be fantastic.

    • I have the same problem. Temp = -1766.2 and Humidity shows 998.

      • Humidity is fine for me, it’s just the temperature. Hmm, I may have to call support and see what I can do.

        • Try external power instead of USB power. Mine is working now.

  • What the purpose of the milled out channels in the middle of the board near Humidity and Pressure?

    • Maybe isolation for the temperature sensor? This may keep the heat generated by other components on the board away.

      • Close - it’s isolation specifically for the HTU21D humidity sensor, but I’m sure the temp. sensor benefits too. The HTU21D datasheet recommends this pattern for ventilation slits, along with clearing copper layers (which has been done, based on the picture of rear of this pcb).

        Btw, its not 100% clear based on the pcb picture, but it seems D6 may not be grounded (due to the gnd fill being pinched off by the through-hole connector). However, D6 is for neg. volt. protection on ‘RAIN’ and not critical to operation.

        I’ve been considering putting together a weather station - this is a nice collection of sensors on one convenient card, may finally give it a try.

        • You had me a little worried about your ‘D6 not grounded’ comment. I double checked the layout and the diodes are correctly grounded. It’s a bit hard to explain but the ground pour does go underneath the 2nd diode.

  • Hey all. I am new to Arduino and lost some hours with the light sensor on the weather shield. I had strange readings when I put on a LED-headlight for testing purposes. The value on A1 went up but came down again to initial low light value without a reason. You guess what happend.. the sensor is so fast, it reacts on the fast flashing of the 1W LED headlight. After putting a 10uF tantalum condensator from A1 to ground, everything works fine. I guess you may encounter wrong values also from flashing of 50Hz or 60Hz lighting. So it turned out, the board is fine, all the sensors seem to deliver correct values. Hope that helps, have fun!

  • Hey all. I am new to Arduino and lost some hours with the light sensor on the weather shield. I had strange readings when I put on a LED-headlight for testing purposes. The value on A1 went up but came down again to initial low light value without a reason. You guess what happend.. the sensor is so fast, it reacts on the fast flashing of the 1W LED headlight. After putting a 10uF tantalum condensator from A1 to ground, everything works fine. I guess you may encounter wrong values also from flashing of 50Hz or 60Hz lighting. So it turned out, the board is fine, all the sensors seem to deliver correct values. Hope that helps, have fun!

  • Is there a timeline as to when these will be produced? I could really use one for a project I want to do.

  • What is the lifetime of one of these, a connected arduino and an xbee transmitter? Someone mentioned their’s lasted six months, but that seems short for the cost of the boards. I am a complete noobie though so what do I know

  • i just want to ask if i will order this, what is the estimated time of arrival.? my location is philippines.

  • Well, after 6 month of operation, my Weather Shield finally quit working. The MIC5219 died and now there is a short somewhere on the 3.3V supply. It could be anything… The shield was outside, in a waterproof enclosure. Time for a new one or move on to something else?

  • I have spent past few week doing set up and I cannot figure out what I’m doing wrong. im using (Arduino + XBee + Weather) as my hardware. I have the weather shield and the XBee shield and I can only get the weather stuff to work with (displaying on the serial console). plug in Xbee the wifi cant find the Xbee or the wifi to work (sending some data to Sparkfun Data) but it I try to get them both working it seems like the communication with the XBee gets trashed. i put Xbee on top on weather shield and weather shield on top on arduino Uno. Would love to see how you’ve managed to do this…any hints would be appreciated!

  • Any chance this can be used on a 3.3V Arduino Due with some mods ?

  • Is this easy to integrate with a Beaglebone or Beaglebone Black using a Proto Cape and mini breadboard? Sounds like a good first weather project.

  • Is this easy to integrate with Beaglebone and Beaglebone Black with a BeagleBone Black Proto Capem and mini breadboard? This looks like a good first weather project,

  • I am building a weather station using the wimp weather tutorial and I’m a little confused by how this is being powered. I didn’t see a good explanation in the tutorial but it looks like it is supplied power through the electric imp from the Sunny Buddy and wired to the 5V pin? I am currently supplying power through the barrel jack on the Uno which works with a wall plug / 9 volt battery but doesn’t work with the power from the Sunny Buddy, when connected this way it appears to not gather info from the weather shield and reports no data to send then goes to sleep.

    I am pretty new at this so any help would be greatly appreciated.

  • Weather Shield and pcDuino I have had mixed success using the Weather Shield on a pcDuino 3s. I have loaded the latest kernel (20140721) and the latest lUbuntu (20140430). I also have loaded the pcDuino with Qt version 4.8.6 and Qwt 6.1.0.

    My first attempts to duplicate the output of the Weather_Shield_with_GPS sketch running on an Arduino Uno resulted in many discrepancies. * I could not get the serial output to work. Several web queries leads me to believe that the SoftwareSerial library does not work on the pcDuino. So, I turned the switch on the Weather Shield to route the GPS output to UART2. This did not work at first until I obtained a copy of the setuart2 program that can be used to turn the UART on or off. Now, I was able to receive and process the GPS data.

    • While the HTU21D module’s humidity and temperature seem to be working properly, the same could not be said for the MPL3115A2 pressure and temperature. I have not yet determined why this the case. It should be noted that the HTU21D readings returned are skewed by the heat given off by the pcDuino board.

    • The readings returned for battery level and light level were wrong. The light level never seemed to change. I finally determined that there were two problems. First, the value of /proc/adc1 which should be the light level always seems to be 63 no matter how much light is shining on the light sensor. However, I discovered that if the unused AD0 pin is grounded (I don’t have the optional wind and rain sensors), then the value of adc1 (/proc/adc1) would change. However, the program still didn’t display a good value for light_lvl. This turned out to be because the ad0 and AD01 pins are only 6 bits resolution instead of 12 like the others. So, the value returned has to be shifted: change the get_light_level function line where the light sensor is read from: float light_sensor = analogRead(LIGHT); to float light_sensor = (analogRead(LIGHT)<<6) | 0x37;

    I have developed a Qt graphical application using the Weather Shield and would be glad to share my code. And if anybody knows why the MPL3115A2 doesn’t work, I’d appreciate it.

    • I may have come up with a solution to the MPL3115A2 pressure reading. Unfortunately the fix is probably curing the symptoms and not the real cause. To get it to work, I had it read an extra byte, i.e. 4 instead of 3 and then discarded the first byte. Now the pressure is calculated properly.

      In addition, the temperature appears to be read correctly if you read 6 bytes and throw away the first 4. The conclusion is that the TwoWIre class is ignoring which byte to read and always starts at byte 0.

  • I’m using a Minnow board, and the I2C isn’t working. Specifically, the ACK bit is oscillating. Looking with a scope, I see the start, an address (C0, write to pressure sensor, then a bit time of oscillating levels (alternating ones and zeros at a much higher frequency) when there should be an ACK (low level). Any suggestions?

  • Can you confirm which pins are not used ? If I read the schematic correctly ( a bit of a leap) it looks like 9-13 are unused.

    I have successfully gotten the XBee Wifi and the weather station to post to and I am (with help) integrating the lightning detector into the software. I need one more pin to create a custom interrupt.


    • Lightning working with some major help from a friend. Cleanup in progress

    • Yep! D9/10/11/12/13 are available to be used. You can even cut the traces to status LEDs and use them if you need.

  • I am having a problem with the humidity sensor. When I power up the board, the humidity data is negative. The data eventually switches to positive (example: switching from about -68% to 56%), although this can take less than a minute to almost 10 minutes. The Temperature data is fine, and I am using the HTU21D_Arduino_Example program. Does any one know what’s going on? Update: the humidity sensor is bad - returning to sparkfun.

  • Anyone tacked on a lightning sensor yet ?

  • I just bought the weather shield and weather meters and I am trying to make it work with Arduino UNO R3.

    I connect everything like in the hook up Guide.

    But when I run the example you provide, I get this wrong values.


    Arduino is connected with the shield through stackable headers like the example and the meter is attached with 2 x RJ-11 6 pin coonectors.

    I am running this on a retina mac with 10.9.4 OS and 1.05 Version of Arduino

    Could anyone help? cheers

  • Hie guys, does this module work with the netduino plus? does anyone have any pointers to code, instructions? thanks

  • This all works fine on my duemilanove/328 but when I try it on my Mega/ADK with the same sketch and same shield, the humidity, temperature and pressure are wacky. Do I need to change something in the i2C setup in the sketch for the Mega? These readings are what I get and they don’t change: humidity=998.0,tempf=-1766.2,pressure=-999.00

    The suggestion below on using separate power makes no difference in my case. Any thoughts?

    • Ah, figured it out. SDA and SDC can be accessed directly on the Mega with pins 20 and 21. Just needed some short leads and it works perfectly on both boards now.

  • Hi, I cannot find this shield in the Fritzing software, could someone help? Thanks

    • Hi, I don’t believe this is a default part in the Fritzing software. It also doesn’t look like we have added this part to our Fritzing library. You can check online to see if someone else has made this part for Fritzing, otherwise you might need to make it yourself.

  • I have some problems with the shield. First the temperature from the HTU21D seems to be a bit to high. Second the MPL3115A2 was working fine for the first few days. But now both pressure and temperature is way off (and not changing): 481.27hPa and 34.94C (it really is 1017.9hPa and 25.6C). Also the “Who_Am_I” register is supposed to return 0xC4, but now I get 0x2E for some reason.

  • How do i use Arduino Yun with the SparkFun weather shield?

  • I am using weather shield with my arduino yun. im getting 998 for my temperature ,humidity and pressure sensors. how do i solve this problem?

  • How do you use the Weather Shield with a Mega R3. If not as a shield then what pins do you use? Also can you use it with a Due?

    • Because the I2C lines are broken out to the R3 this should work on the Mega. Keep in mind there are also things like interrupts which might not line up right though. As for the Due, that’s a bit trickier. All the sensors seem to be running at 3.3V so it might work, but the interrupts are going to be even harder to get working on the Due. For more information email

  • Hi guys, I have an issue with the software. The generated results from my humidity and temperature sensors while connected to an arduino hardware gives a constant 5volts. The sensors a4 and a5 are HV_SDA and HV_SCL respectively. I am unsure if there are coding required to activate these sensors, or would any resistors be required to enable the sensors to work? Any assistance is greatly appreciated! Thanks!

    • MartyH / last year * / 1

      Are you running the example software? Also make sure that you’re using the latest libraries. And check your headers.

      example & libs

  • i keep getting “temperature:998.0C Humidity:998.0%” for my readings. Whats the problem?

    • And remove any pull-up’s on your I2C lines.

    • Nate / last year / 1

      Hmm, are the header pins soldered correctly? 998 is an error code that indicates the I2C is timing out. Double check that the I2C pins are connected. If you continue to run into problems feel free to contact tech support.

  • So I have both the old weather board and the new weather shield and while my opinion is unencumbered by the thought process, here it is.

    I know Sparkfun is updating the weather board but I like the shield better. Having an Uno underneath is less of a burden and it does make the whole process of development simpler. My suggestion would be to add a second shield. Take the current Xbee shield (which I love) and add LIPO charging circuit, an I2C RTC, and an SD slot. This would take the current shield and make it easily standalone. Xbee for wireless, LIPO for remote power, the clock and shield to store data if the wireless link drops. The Weather board will end up pretty dense pretty fast and having 3 boards isn’t a big deal.

    Just my thought

  • Can the GS407 gps unit be used with this, in place of the GP635T?

  • Sparkfun, What is the minimum number of pins required to use this shield and get all of the data from it? I am looking at locating this away from my Arduino in a separate enclosure and connecting it via an 8 conductor cable and RJ-45 connectors. Will 8 conductors be enough or will I need more? Thanks.

  • A sensor that measures Solar Radiation in W/m2

  • A sensor that measures Solar Radiation in W/m2

  • Is there something for Solar Radiation Sensor?

  • How accurate does this read the temperature? I thought I remembered reading + or - 0.3 C, but that seems like a big error.

  • Im looking to connect this to your weather meter (so far so good) and transmit wirelessly to a raspberry pi. However, I would like to connect this straight to an Xbee, without the Arduino. Basically keeping it even simpler. Is that possible?

    I got the idea from the Wired ( but that’s using your old board.

    Of course, otherwise I would simply have to go with an Arduino, but it’s another thing to program and maintain that could break when the -20c winter comes :)

  • Just got my weather shield, but forgot to order headers. (In my impatience) I slapped on what I had, forgoing VIN, and pins 8 and 9. It took me a visit to the schematic to figure out why I was getting bogus values without VIN connected, but now that it’s working I’ve still run into some interesting issues with the example sketch on the Leonardo:

    1. The serial seems unreliable, starting indeterminately. I think this is a known issue with the serial reset on the Leonardo.
    2. When serial data is being output, everything looks in order, except for the rain sensor. It just keeps racking up values despite being disconnected.
    3. After the anaeometer spins for the first time, serial data is only output when the aneometer is still spinning. Otherwise it stops sending.

    Any suggestions?

    Edit: Guessing that this is an interrupt problem, further inspection of the datasheet reveals that the anaeometer is supposed to close a switch once per revoluion, but checking it on a multimeter it’s actually a normally closed contact that opens when the magnet passes. Did I get a deffective/different anaeometer, or is this just an interrupt issue?

    Edit 2: I isolated the issue to interrutps being fired whenever working with the I²C bus to read the barometer, etc. The Leonardo uses pins 2 & 3 for I²C, so an interrupt gets fired every time data is sent. As a work around in software, you can detach the interrupts for the weather sensors before using I²C data, and reattach them when done.

  • I am using this with the weather sensor kit. Mostly working, but I noticed that with the rain sensor, i’m getting some false readings. It seems to be worse when the units are outside, but I get them inside as well. I left it running indoors for 12 hours today and measured .03 inches of rain, yet the house was quite dry. :-) When the sensors and arduino were outside (arduino was under an enclosure and on a covered patio) the number of false readings was much greater - every few minutes at some times. Any clues?

    • I managed to catch some of these interrupts on the logic analyzer. Very short duration drops, like less than 100 nanoseconds. Changed the interrupt handler in the sample code to confirm the pin is low. Seems to work better now. Maybe the pull-up just isn’t enough at times? I found the same problem with the wind speed by the way. Taped it in position and still saw occasional clicks. Much less of an issue there I think since it takes so many to get even 1 mph of wind speed.

      • Hmm, this is very interesting. Thanks for coming back to tell us what you found. I have seen one or two rain gauge ‘measurements’ on the station on top my house that don’t quite match to conditions. I’ll see if I can replicate the short pulses you’re seeing.

        • I have a La Crosse WS2310 that periodically tells me wind is 100+ mph (When dead calm) - it looks like this uses the same sensors. There are some things you can do to reduce sensitivity to noise. The long wires pick up noise from lightening etc. Took a while to find the link again. Reminds me that I still need to do this.

  • The status LEDs should be labeled “Blinding Blue” and “Is It On? Green” since the mcd ratings are not matched. =P Or is that so the light sensor can measure the dark? I feel the ambient light sensor circuit needs some work… Mine reads 0.00 right now sitting above my monitor in very softly lit room. I’ll probably grab a few to experiment with an op-amp.

    I wish I looked at the schematic closer before purchasing; the Wind pin-out is not compatible with the Davis anemometer I already had lying around.

  • hi, i am interseted in using the weather station (and the weather board)with the arduino ethernet shield.Is that possible to happen and how it will be the best to put together the three boards (arduino+ethernet shield+weather board) I mean which comes first is it of any importance?if you know any tutorial regarding that I would be grateful too thank you in advance!

    • I suggest putting it top most so it is more exposed to the environment. I used these longer non-stacking pins on my boards:

  • How can I get the sensor library files that are needed to run the example program for the Sparkfun weather shield? Looks like I need 3 libraries, HTU21D, MPL3115A2 and maybe ALS-PT19.

    • Have you had a chance to look at the hook up guide? All the software is over there. If you just need the two humidity and pressure libraries you can grab them here.

  • I tried to use the libraries in mpide because i use chipkit of digilent, when i compile the program show me problems about wire.h can you help me please to solve this problem?

  • Below freezing I got some strange results using the example code. It appears that MPL3115A2.cpp does not take into account the 2’s complement nature of negative numbers used by the device; (see Application Note). The following shows additions to readTemp() which appear to fix this:

        word foo = 0;
        bool negSign = false;
        if(msb > 0x7F)
                foo = ~((msb << 8) + lsb) + 1;  //2’s complement
            msb = foo >> 8;
            lsb = foo & 0x00F0; 
                negSign = true;
    // The least significant bytes l_altitude and l_temp are 4-bit,
    // fractional values, so you must cast the calulation in (float),
    // shift the value over 4 spots to the right and divide by 16 (since 
    // there are 16 values in 4-bits). 
    float templsb = (lsb>>4)/16.0; //temp, fraction of a degree
    float temperature = (float)(msb + templsb);
    if (negSign) 
        temperature = 0 - temperature;

    This affects pressures also, if there is a negative value.

    Note that -999 results indicate a timeout. In the cpp, the timeout values have been increased versus other examples.

    Also, there was question about the Ethernet shield. It’s fairly easy to combine this code with the Arduino BarometriPressureWebServer example. But, keep in mind that the Wiznet W5100 is quite hot and very close. It added about 10F at room temperature.

    It’s 1.1 degrees Fahrenheit right now. Sorry about not knowing how to use GitHub…

    • (headsmack) Thanks D.D.G.! I forgot to test the sensor in the freezer. I’ve pushed your fix to github and the tutorial. It compiles but I haven’t been able to get the sensor to negative temps yet. Please double check my work and thanks for helping out!

      • Nate, I think the library is over with the breakout board on github. I added it to the shield example and it’s working fine… in my freezer.

  • Got this board and ordered the anemometer/rain gauge. I’m trying to make this wireless, but I’m somewhat of a newbie. I was hoping to use XBee (series 1), and I have the parts needed, just having trouble on the software/comms side. The Xbee tutorials seem to use a much older version of the X-CTU, and I can’t find how to set up the XBees to my network. Is there a better way to do this, or someone willing to help dumb-down the XBee comms for a newbie? Thanks!

  • Brain freeze the units are good. I mistook psi for in" of HG when comparing. (I wish we would just move on to SI units like the rest of the world) Ken

  • Cool Board, I am having fun with it so far. Working to make it solar powered and log to a SD card to “duct-tape” to a hang glider.

    I am getting a nonsensical value out from the pressure sensor. 94967.75 What units are these? The data sheet claims Pascals. I am at about 610m. The altitude reported is 548m (in altitude mode). This is much closer than the pressure value reported yet is not corrected to known weather pressure conditions. Raw pressure would be more useful to me in my application.

    The values change with altitude with sensitivity that seems to be within the 30cm.

    Thanks for any comments or ideas Ken

    • Sounds like you got it figured out. The pressure sensor outputs readings in Pascals. Check the example sketches and let us know if you run into any other problems.

  • I’m using this shield with the freetronics EtherTen Aurdino clone and it came right up using the provided libraries. I have noticed that the HTU21D always reads 1°C higher than the MPL3115A2, and both seem to read a bit warm. I guess I need to calibrate them and adjust the readings in software…

    For anybody else using this with the EtherTen, you can cut out a slot in the weather shield where the RJ45 jack protrudes. This cuts the traces to the dedicated I2C pins (for R3 arduinos) and the serial wires (for GPS). You don’t need the I2C pins with the EtherTen, and if you need to use GPS, you can add the serial lines back with a couple wires. This allows the weather shield to seat onto the EtherTen without extra spacers. The only negative is that it places the sensors about 1cm closer to the warm chips on the EtherTen. Also, it voids your warranty and removes the SparkFun logo, so I guess those are negatives too ;)

    • I have noticed that the HTU21D always reads 1°C higher than the MPL3115A2, and both seem to read a bit warm. I’ve got exactly the same behavior. Have you got any fix / explanation to this discrepancy ?

      • Sorry, I don’t have a good reason why one sensor may be higher than the other. Calibration is really going to be required if you need to get 1°C accuracy.

      • Unfortunately, no. I’m just using the MPL temperature, since it seems to agree with other thermometers.

  • Will this work with the ethernet shield too ?

    • I am using this board with the Ethernet Arduino (not shield, The SS for the SD card on pin#4 conflicts with the GPS TX. So I pulled out the header pin and hardwired #4 to #9 on the Weather Shield. Works fine.

  • Will this work with the Yun?

    • Just got a Yun and the weather shield this week. Out of the box they will not work but with some simple changes you can get most of the features working.

      I was looking to record temperature, and humidity, and I now have this working with the Yun and the weather shield.

      As noted here the two wire interface on the Yun is on D2&D3 as opposed to the UNO which is on A4&A5. The temperature, humidity and pressure sensors on the shield are wired to A4/A5. So for now I have jumped A4 to D2 and A5 to D3.

      Second, the weather shield wants power via VIN which it regulates to 3.3V for the pressure, temperature humidity sensors etc. Unloaded there is 5V present on VIN on the Yun but as soon as you plug in the shield it goes away. Simple solution is to jump 5V to VIN (I am powering Yun via USB). Note there is a warning about VIN on the YUN spec sheet.

      I now have the example code running, but I removed all of the code related to wind, and rain because of the jumps I made above (Wind and Rain are on D2 and D3).

      • Thanks your post gave me the key piece of information that I needed to get the Yun working with the wind, rain, pressure and humidity sensors. I used a soft I2C library( ) so interrupts are no longer an issue and ported the libraries that Sparkfun provide for each of the sensors. Anyway incase someone finds this useful I have posted the code here: This has only had a very quick test, 5 minutes on my bench, so there are probably lots of bugs lurking in the code. To get this to send back weather information you need to send a W over the serial line.

    • I started testing this unit, and I was able to get the Yun to output data from the example code. But, you can’t use the rain or wind sensors. The rain and wind sensors are on D2 and D3 because those are the interrupt pins on the ATMega328. While they are also the interrupt pins on the ATMega32U4, they are also the I2C pins on the ATMega32U4. Because the sensors on the board are I2C, this means there is conflict with the Rain/Wind sensors. The logical resolution would be to connect the rain/wind sensors to the ATMega32U4s interrupts, but, the ATMega32U4 only has them on D2, D3, and D7 (and the hardware serial lines which are not available on the YUN). In other words there just aren’t enough free interrupt pins to use the rain/wind sensors. If you aren’t using them it should work though. Keep in mind that the shield will short A4/A5 and D2/D3. Also with the Yun the Ethernet jack is tall enough that no shield will fit on it well. I would just get an extra set of stackable headers.

      • I’m attempting to use a soft I2C library( to get this shield to work with the Yun, but I’m noticing some odd behaviour. Here what I have tried so far. Firstly I got the the MPL3115A2 breakout board working with this library, basically converted the sample sketch with an Arduino Duemilanove. Then once that worked I got the humidity sensor to work and did a simple sketch that read from both sensors and plugged in the weather shield and it worked, much to my surprise. I also tested this with a Uno.

        Then I repeated the same process with the Yun, the MPL3115A2 breakout board worked but the weather shield did not, with Simple humidity/pressure sketch or the weather shield sketch. The other odd thing I noticed that the rain and the wind interrupt had to be swapped to read correctly.

        So can anyone here shed some light on why this may be so?

        I can share the code if anyone is interested, once I’ve tidied it up.

        *UPDATE: I got the Soft I2C to work with the weather shield and Yun when I plugged the 5V pin from the Yun to the Vin pin on the Yun, not too sure why this works because when I measured it they were about the same voltage. I will wire up the wind and rain sensors when I have time and report back if they work.

      • Thanks for the research…much appreciated.

    • I would also like to know if it works with a Yun. Or what I would need to adapt the weather shield to the Yun. Thanks in advance for any help or tips! (no guesses please, I am interested if someone has actually done it, I know you guys can make anything work :-) but I would like to have a little head start and know the Yun and weather shield really play well together :-).

      PS: FYI I noticed today (Dec. 11) the GPS module and the rain/wind sensor package are on backorder :-(.

    • I haven’t tested the weather shield on a Yun but it should work.

      From Arduino’s site: The Yún’s 32U4 functions in the same way as the Leonardo, except you cannot use Serial1.

      The weather shield works swimmingly with the Leonardo so it should work just fine with the Yun. The major interface pins are the I2C bus. Everything else is just GPIO. The ATmega32U4 on the Yun should work well.

      • Hardware wise it might work then, but what about conflicts with the bridge library. Can it please be tested and let us know if it actually works?

    • Any feedback yet? I know the I2C pins are different on the YUN/Leonardo vs Uno etc. Sparkfun have you guys tested this on the YUN? If it work I want to order a few!

  • Does this require a 3.3V Regulator on the Arduino Board?

  • Temperature sensor?

  • Let’s see now - The light sensor is buried on the board. So if we are in an enclosure (ventilated) there is no way to determine the light outside the enclosure. Is there any way to remote the Light sensor? Other than that it looks like a great board. I will be ordering one soon.

    • I agree, many of the sensors are directly on the board. I was planning on using this in an environmentally stable enclosure (no light, controlled temp, weather proof, dust proof, etc). It would be great if this board had the sensor connect via connectors, so that I can locate the sensors outside, while the shield, arduino and other electronics are safely inside. Looks like I’ll have to build my own version and use this board to prototype the software with.

      Another thing that I noticed, the weather shield and the ProtoShield (DEV-07914) both do not fit on the Arduino Uno, Arduino Ethernet Shield, or the Arduino Yun. They all make contact with either the ethernet connector metal case, the USB-A port, or the USB-B port (on the Uno) and cannot be fully seated on the headers. I presume metal around the ports are all grounded and would therefor ground this shield and the ProtoShield (leds, resistors, and switches). Not sure which Arduinos the shields will fit on.

      EDIT: (SOLVED) I inserted an additional set of stackable headers (PRT-11417) between the Arduino Board and the Weather Shield. Additionally, I’m going to use the weather shield as is, since it has the pressure sensor, rain and wind connectors, etc already, and they will work within the enclosure. The on board humidity and temp will give me data for temp within the enclosure. Then, I’m going to add an additional board on top that will have a RJ-11 connector that I’ll connect additional temp and humidity (for inside and outside of my greenhouse) via I2C to multiple HTU21D Humidity Sensor Breakout (SEN-12064) boards.

    • I was about to set out on the project building comparable functionality out of the Arduino FIO (need XBee to communicate the data points), so this definitely looks like a product that could save me some time. However, like the prior poster, I’m at a loss as to how to weatherproof this board and its enclosure.

      • I use a weather tight box that opens on the bottom. I cut an opening on the bottom and covered it with a screen. This fits inside my solar shield (from Ambient Weather) which makes it weather proof and alows the temperature and humidity to be read. This way you get double protection.

    • You could always add a light-pipe ( or possibly fiber optic cabling ) that extends to the outside of your enclosure. You can always handle the variances in software.

      • That sounds like a good idea. Fiber optic will transmit the light with little loss. A multi fiber bundle would get even more light.

        Thanks john

        • How about a transparent box? - you get the bonus of a cool view of all your gear. This will also help in early detection of moisture issues.

          • Clear box would be really bad idea since the light source would be the sun and that would obviously cause the temperature sensor to not give accurate results.

            • While what you say is true, it also applies to any enclosure - a black box with a lightpipe/fiber optic would certainly suffer from solar heat gain as well - at least with a clear enclosure you could add a foil shield to reflect the solar radiation and hopefully mitigate this gain.

Customer Reviews

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Weather shield not suitable for outside environment

I have just completed interfacing the WS to a chipKIT Pro MX7 mostly because I wanted to look at the sensor performance. The pressure sensor requires some tuning of the I2C register read function in that there is a delay between when the pressure sensor is commended to take a measurement and when the data is available. The Hold mode doesn’t appear to work at all. To use the No Hold mode, I needed to inset a 50 ms delay between writing the command and reading the measurement. The barometer reads about 2.56 in Hg low. The humidity sensor reads about 3% RH low The temperature measurements between the pressure sensor and the humidity sensor differ by 1 degree F and both read about 6 degrees F high. This may be due to my hardware configuration. These sensor measurements were compared to a General Eastern Model 900 Thermal-Hygrometer.

The light sensor doesn’t appear to have much functionality since the WS circuit board cannot be exposed to the outside environment.

The bottom line is that I believe I will bet better results using sensors packaged individually but it was fun to play with.

Hi, Thanks for the feedback. We have used these in long term outdoor projects ( however, you do need to take specific consideration to how the device is housed outdoors. You could certainly build a system using individual components as well if that’s feels more user friendly. Happy hacking!

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