DIY weather station mainly for rain?

I have a Version 3. Does anyone think this is possible?

Problem: I can’t get accurate local rain data. There were thunderstorms and heavy rain sunday evening and on monday the zones are only ~50% full :frowning:
Solution: Create a DIY weather station with arduino ESP8266 mostly for rain sensor only. Hook it up to weatherunderground and use it as a weather station in rachio? Can rachio get rain from a weather station and rest of the stuff from other weather station?

I see ~$150 wifi weather stations on amazon but I have a few ESP8266 laying around from previous projects and I don’t need wind, temperature and other stuff and that is mostly accurate from other sources. It is the rain that is not accurate.

Has anyone done a similar project before?

I’m not certain that you can get onto the wunderground system without more than a rain sensor…but I could be wrong.