The DHT21 digital temperature sensor is one of the commonest from the range of DHT temperature sensors and boasts a relatively high-temperature measurement accuracy of 0.5oC in 0.1oC steps with a relative humidity accuracy of +/- 3%. It has only 3 wires, including power and ground, meaning only one digital pin is required to interface it to a microcontroller. For Arduino development platforms the sensor is very well supported by the DHT library available from the Arduino Playground website.