To understand how the humidity in my apartment changes I built a sensor that records a few metrics about my apartment. It’s constructed entirely of parts from Adafruit, notably built on the WiFi Feather. Beyond the humidity sensor, I also added sensors for barometric pressure, air quality, lux, sound, and acceleration. It sends all the metrics every second to my desktop via UDP, where they are stored. I’ve only got one day of data so far, but I’ve been using Metabase to graph the metrics and it’s worked very well.
Source is on GitHub.