I live in a central Texas town about 5 miles from the official weather monitoring facility at the airport. I have a rain gauge in the open and so far this year, I’ve recorded 50.5 inches of rain. The official total at the airport is 33. I call BS.
While that may seem like a huge difference, it is possible. I live 5 miles from where I work.
Many times I have talked to my wife on the phone where it would be raining either here or there and not at the other.
Heck, I’ve seen it rain across the street from my house but not on my side!
The company where I work makes Hygrothermometers (among other things) for NOAA, FAA and the NWS. They measure the Dew Point and the Temperature using precision Platinum resistive temperature detectors and a electronically chilled mirror sensor.
We have systems installed all over the country and foreign places and onboard ships as well. Whenever you see these things on TV or the news, chances are I worked on it:
http://tslinc.com/systems/instruments-hygrothermometer/