Building a thermo-hygrometer using Arduino

August 23rd, 2026

During the heatwaves in Europe, at some point I was (unnecessarily) interested in the temperature and humidity in my house. Since buying a ready-made thermo-hygrometer is too boring, I decided I would make one myself using the Arduino platform. Happily all components arrived just as temperatures have gone back to normal again!

For this small project, I’ve used the following components:

Arduino Micro;
Adafruit DHT20;
Otronic 1602 LCD display.

Note that both the DHT20 temperature and humidity sensor as well as the display have an I²C module, making interfacing to and from the Arduino much easier. As long as all connected I²C devices have a different bus address, they can be connected to the same SDA and SCL pins on the Arduino.

To get the readings from the DHT20 sensor, the Adafruit_AHTX0 library is needed; to control the display, the LiquidCrystal_I2C library is required.

A photo of the Arduino-based thermo-hygrometer, with the display showing temperature and humidity in the foreground.

Every two seconds, I obtain the sensor readings from the DHT20. I then parse these and print them onto the LCD display (with a little smiley indicating whether the values are in a decent range). It’s a very simple project but I enjoyed working with it, and definitely has made me want to add more functionality (such as a button to switch between other information on the display) and do more extensive projects.

Click here to download a ZIP archive with the code and a wiring diagram.

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