One of the knocks against many of our sites is the disregard for standards in installation. I admit that my site is far from ideal. The temp seems spot on for a reasonably reliable report. The other gauges are affected by trees and structures. I could put work and money into improving the site but it is adequate in meeting my goals.
Now NOAA is the supposed benchmark. It is the basis for the reporting that indicates temperature change. It has stringent standards. Sadly too, it is run by bureaucrats.
A survey was taken of many of those sites. Some sit in the middle of asphalt parking lots or similar roof sites. Paint on Stephens structures was changed in a manner affecting readings. The list goes on.
You can look at the info here: http://surfacestations.org/
The goals of our paper were to (1) determine to what extent the existing USHCN stations satisfied the CRN siting criteria, and (2) determine to what extent poor USHCN siting affects temperature trend estimates in the United States.
The vast majority of weather station sites surveyed are CRN 3 or CRN 4, which are considered undesirable for climate trend monitoring.
Only 80 sites out of 1007 are CRN 1 (best) or CRN 2 (acceptable)
61 sites are CRN 5 (worst)