Here’s the Tl;DR summary of the below: Personal weather stations’ rain meters are constantly getting gummed up. You can probably count on a local TV station’s weather station having their rain meters be accurate.
However, some ‘dude’ in your neighborhood who puts up a PWS might not be saavy enough (or care) to regularly clean out the rain gauge on his PWS, so many of those stop reporting rain after several months.
Details
Several years ago I worked for a pivot irrigation company that also sold weather stations to farmers - that weather data was integrated into the farmer’s irrigation system control.
This weather stations were de facto ‘Personal Weather stations’ that provided the usual PWS data (air temp, humidity, wind speed and direction) as well as having soil moisture sensors (typically four soil sensors at 1’, 2’, 3’ and 4’ depths).
As much as us Rachio users are dialed into our lawns and how the weather affects the sprinkler system, most farmers obsess over it as it’s their livelihood.
That said, almost all PWS systems have rain meters that measure rain amounts in one of two ways: the rain water is collected in a funnel shaped rain basin, and the bottom funnel opening is a small, precisely sized opening that drips onto either a ‘see saw’ sensor that toggles back and forth (more prevalent) or a ‘flip board’ that drops down them back up. Each of those toggle/flip actions is counted vs time by the PWS. Each of the mechanisms is calibrated so that the PWS output provides a very accurate precipitation amount and rate/ hour.
The rain meters described above are much more susceptible to ‘failure’ because of dust/dirt/debris clogging up the rain meter, preventing the counting mechanism to work. Their funnel shape collects junk in it.
All the rest of the PWS sensors are pretty durable - the temp / RH sensors rarely have issues, and the spinning wind cups for the wind speed have sealed bearings, and the spinning motion naturally clears out any debris.
The above was the advice we were telling the farmers regarding maintenance of their weather stations: every few months, go and clean out the rain meter parts, as they get gummed up most often.
My advice: Before you pick the nearest weather station for your Rachio, make sure it’s rain reporting has been accurate and consistent!!
