ESP8266 ultra low power thermometer

see the article here

Specs

1. Arduino-compatible
2. lasts more than 2 years on a pair of AA batteries
3. measures temperature and pressure (BMP280) OR temperature, humidity and pressure (BME280)
4. transmits data regularly to Blynk (or other platform, if you program it for it)
5. can be programmed with just a simple USB-Serial converter

Required libraries

• ESP8266 core
• Blynk library
• BMP280 library