Most PWS stations are fairly accurate. Also, a lot of them you can verify the data.
This explains some more regarding PWS.
If it is a MID_ it is a CWOP.
To search for reliability you can use this URL for CWOP, drop the MID_
To search for reliability you can use this URL for PWS, drop the PWS_
In our weather station selector each PWS has a link that you can click on. Most have available data, some will not.
Thanks for the feedback, it would be great to have an aggregate of data. This, or get much higher resolution satellite data that could be just as accurate, but even more so.
Thanks again, I'll pass this along to the product team.