As simple as it gets ESP8266 weather station on top of my ESP8266 KISS, powered by a 18650 Lithium battery and a solar panel
http:https://www.billy.gr/esp8266-kiss/
DS18B20 temperature sensor on D3/GPIO0
BME280 I2C Temperature Humidity Pressure Sensor on D2/D1 (GPIO4 SDA/GPIO5 SCL)
Battery Voltage on A0
D0/GPIO16 needs to be connect to RST pin to return from deep sleep