If you need a temperature sensor and relay in one device, you should look no further than Thermostat click. It can be used to measure environmental temperature and to directly switch ON/OFF cooling and heating devices, performing all the functions of a thermostat.
Thermostat click carries the MAX7502 IC digital temperature sensor, that also provides an overtemperature alarm/interrupt/shutdown output, and an SN74LVC1G126 single bus buffer from Texas Instruments. MAX7502 IC can measure temperatures from -25°C to +100°C, within the accuracy of ±1.5°C.
The G6D PCB power relay can control up to 5A, 250V AC/30V DC loads.
The click runs on either 3.3V or 5V power supply and communicates with the target MCU over I2C interface.