Or they locate the measurement equipment housing on the grass in the corner of where two large black asphalt tarmac ramp areas come together, so when the wind is from the west through the south the reading is not compromised, but when it is from any other direction (and especially from the NE through the SE), the wind passes over hundreds of yards of tarmac before it hits the gages.
This was the case at the Columbia, Missouri Regional Airport (COU) until just a few years ago when the station was moved a few hundred yards to the south. So, for about 20 years we had really bad readings or not so bad readings from this station depending on the wind.
A concerted effort must now be made to peer-review the location history of each station and to only use data from stations that are determined to be accurate. All other data must be disregarded.
Weather stations at airports are there to provide data for pilots about to take off or land. They are NOT meant to provide the average reading across a valley, etc.
Tucson used to hit 102-103 in the summer. Now it hits 110-115...unless you go a few miles out of the city, where it is (drum roll, please)...102-103 on a hot summer day.
Global warming is all about statistics, and how they are interpreted.