Building a Arduino Based Weather Station

One of our interests is weather monitoring. It seems like a natural thing for a ham radio operator to be interested in, so we applied our micro-controller expertise and came up with the following project. In it’s current version, it tracks humidity and temperature, but we have plans for adding barometric pressure (we blew up our first baro chip), wind speed & direction, a rain gauge, and solar intensity. It can also be used as a thermostat / climate control system.

We used a Sensiron SHT-21 Temp/humidity module, a Arduino Uno, and a 4 line white on blue LCD. If you have problems finding the SHT-21, I’ve been told the DHT-11 is a good (much cheaper) substitute, but I’m sure there will be code differences. Here is how we built ours:

You can also get a complete kit that has all the pieces!

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5 Responses to Building a Arduino Based Weather Station

  1. George B. says:

    Off topic for weather station, on topic for those still considering an Arduino project…

    Thanks Steve for Posting another project for the Arduino, as Bill Knight has mentioned, this is a good place to start learning how micros can assist us, especially off grid..

    I want to mention the conversion of my Ford Think, I do it because no one wanted to buy it from me, and the cost of repair was too much in comparision to others for sale. With that said I might offer an example of purpose for the Arduino in the ford think Project I posted..

    That gas pedal in the Think, it’s electric! That carb is back there a ways and takes a mechanical cable. Here’s an example of one:

    Now the question, What’s easier and cheaper, place a servo at the carb and talk to it with the electric gas pedal via the arduino, or? Will I stop and inventory all the other things on this car that could make use of a CPU, BEFORE I COMMIT to ripping it all out, and using the 1880s solution? Some will consider the mechanical solutions the best and more dependable, but I will at least consider the possibilities.

    Of course the next thing that pops into my head is that choke, do I use yet another cable? Another hole in the dash? Of course I think about the Honda speed control I bought from the salvage yard, wow, that is a nice part, all set up to move a cable to any position according to a command.

    And then, exactly how does the rest of this stuff in the Think work? Lights, turn signals, Speedo? I should at least stop and TH!NK before I commit to a plan. The Arduino could take a lot of orders and process them, the small Motor Cycle Alternator means we should give head light and tail lights some thought. LEDs could be the smarter choice.

    That pedal 0-5 volts, the micro’s built in ACD would scale that perfectly, and that model Air Plane Servo ready to receive the order. Of course, there’s that choke, it works the same way with a different program.

    But NOW! here’s where the DIYer brain heats up! While your neighbor says “just call the man”, all of a sudden you realize you can write a line of code to optomize things. OK I give an example:

    Another very simple device is a thermistor, we can use it to know the temperature, we might use this in a ‘start’ routine, when the engine is warm, no choke, when dead cold, more choke, we might even have a pickup at the coil and know the rpm, we might let the Arduino control the idle. We walk before we run, but at some point, we can simply go back and optomize the code.

    Then the DIYer drives his mind into the ditch! All of a sudden you see that O2 sensor in the exhaust, and a valve with another servo that could alter the fuel air mixture and optomize it for the best milage.

    All of a sudden your mind jumps back to that Geo Metro that was burning valves because the EPA forced the manufacturer to run lean to heat up that CAT soonest, you see your adjunct now looking at the output of the O2 sensor and making adjustments for best MILEAGE instead allowing your exhaust valves to burn and create even worse emissions..

    Then you hear a knock at the door! there’s a white Van in the drive! Two armed dudes on the porch. It’s the EPA!

    You wake to find you’ve just had another Arduino dream! It’s what happens to the DIYer once exposed, and you should be aware… some drugs are addictive…. for people like us, the arduino can be too as it is no more than a new tool box, full of tools we may have never played with before.

  2. Jetguy says:

    I thought I would share this link of cheap parts do to some of the same functions. Not bad for $20.

  3. bob g says:

    consider a momentary button switch on the dash and a solenoid to activate the choke, cheap/dependable/easy.


    (this coming from a guy that would probably conceive using some sort of multiprocessor scheme to control the choke functions!)

  4. Steve Spence says:

    I’m redoing the weather station with the inexpensive DHT-11 instead of the very expensive SHT-21 temp/humidity module. It will calculate Dew Point. If anyone wants to help out with this project ($25 donation), I’ll send you get a populated breadboard with sensor and functioning code. Donate at

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