The DHT22 is a low-cost digital temperature and humidity sensor with a single wire digital interface. It uses a capacitive humidity sensor and a thermistor to measure the surrounding air and spits out a digital signal on the data pin (no analog input pins needed).

The sensor is calibrated and doesn’t require extra components so you can get the right to measuring relative humidity and temperature.

It is quite simple to use but requires careful timing to grab data. You can only get new data from it once every 2 seconds.