Adafruit_Si7021 community library just published. This is a driver for Adafruit’s Si7021 humidity / temp sensor breakout: https://www.adafruit.com/products/3251
Sensor datasheet: https://www.silabs.com/Support%20Documents%2FTechnicalDocs%2FSi7021-A20.pdf
GitHub: https://github.com/CaptIgmu/Adafruit_Si7021
Have fun!