The DHT22 is a basic, low-cost digital temperature and humidity sensor. 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). It's fairly simple to use but requires careful timing to grab data. The only real downside of this sensor is you can only get new data from it once every 2 seconds, so when using our library, sensor readings can be up to 2 seconds old.

Simply connect the first pin on the left to 3-5V power, the second pin to your data input pin, and the rightmost pin to ground. Although it uses a single wire to send data it is not Dallas One Wire compatible! If you want multiple sensors, each one must have its own data pin.

Features:

Full range temperature compensation for accurate relative humidity and temperature measurement
Calibrated digital signal output for reliability and stability
Does not require additional components
Long transmission distance of up to 20 metres and low power consumption
4-pin packaging for easy connection and fully interchangeable with other modules
Utilises exclusive digital-signal-collecting-technique and humidity sensing technology
Connected with a high-performance 8-bit microcontroller
Temperature range of -40 to 80 Celsius with a resolution of 0.1 Celsius and accuracy of /- 0.5 Celsius
Humidity range of 0-100%RH with a resolution of 0.1%RH and accuracy of /- 2%RH (Max /- 5%RH)
Repeatability of /- 1%RH for humidity and /- 0.2Celsius for temperature
Long-term stability of /- 0.5%RH/year
Average sensing period of 2 seconds
Small size of 14x18x5.5mm and low power consumption
Powered by a supply voltage of 3.3-6V DC and output signal via single-bus
Sensing element made of Polymer capacitor."