The weather station at Fort Collins is located on the CSU campus, and hasn’t moved for over a hundred years. Unlike most of the US, it shows a strong increase in the number of record maximums, and a strong decrease in record minimums.
The weather station started out in the middle of a farm, and is now in the middle of a very busy parking lot and bus terminal.
In 1937, the station was located in the middle of a farm,
By 1950, the area was starting to get built up.
By 1969, the city had surrounded the weather station.
Now it is in the middle of a parking lot.
It must be the CO2.