@heshie75v - If the personal weather station is maintained they can be good, that is why Rachio defaults to National Weather Service stations. Also, some personal weather stations don't report precipitation - which is an issue, so make sure the station that is selected actually reports precipitation. @Gene has a nice write up here -> http://community.rachio.com/t/weather-station-analysis/7715/2?u=gene on selecting a reporting personal weather station.
On a personal note, a neighbor of mine has a personal weather station two doors down. It used to report precipitation fairly close to what I measured in the rain gauge mounted on my fence. Earlier this year the personal weather station started reporting significantly less rain than my rain gauge. I'm guessing there is either an obstruction in the rain bucket or the tipping bucket mechanism is not moving freely.
Another note, if the personal weather station is not yours then you might not know for a period of time if the owner of the personal weather station moved or took their personal weather station down or if it broke. If a personal weather station is selected, the periodically evaluate the reported values with another nearby weather station, preferably a National Weather Service station. Not that the compared values need to match, but they should be reasonably close.
Now if there is not a National Weather Service station near your location or the climate you're in is vastly different than where the National Weather Service station is (e.g. higher elevation - mountains on the Front Range or around Phoenix), then a local personal weather station would provide better data to Rachio for it's calculations. As always, GIGO (Garbage In, Garbage Out).
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