Adafruit TMP36 Analogue Temperature Sensor, 5.5V

Wide range, low power temperature sensor outputs an analog voltage that is proportional to the ambient temperature. To use, connect pin 1 (left) to power (between 2.7 and 5.5V), pin 3 (right) to ground, and pin 2 to analog in on your microcontroller. The voltage out is 0V at -50°C and 1.75V at 125°C. You can easily calculate the temperature from the voltage in millivolts: Temp °C = 100*(reading in V) - 50.