I don't know much about how they go about recording weather at Exeter
Airport but it has occurred to me that the temperatures they report are
always about 1C - 2C above anything else around here in south east Devon at
an equivalent altitude.

The airport is about 6 miles from here and I drive by it everyday. The car
thermometer confirms my own weather data which shows that the temperature
does not change between here and the airport by anything more than 0.5C; yet
I can never get readings as high as the airport's readings - electronically
or manually.
________________
Nick G
Otter Valley, Devon
80 m amsl
http://www.ottervalley.co.uk