Yeah, something is up with how the thermometer/housing is set up. Could be the geography at or around the site. Maybe a slight landscape angle towards the south could cause more directed sunlight/heat. I've noticed that during precipitation events, temps tend to be more uniform with surrounding sites. That would help point towards the idea of more directed sunlight/heat. But (arguing with myself) that wouldn't explain why overnight temps can run signifyingly higher (...but not all the time). Maybe the packed clay soil????? Just some thoughts