john no disrespect since its ask john but I think I know why it is...several factors....one is Indian mounds surround the town and area...which make the town low lying...and the moraines also in area...and the 3 rivers convergence makes it all low lying...heres a topo showing the mounds surrounding the town...and here is a chart which shows it is colder...check out how much colder it is....I was shocked at the data
Prior to the arrival of Europeans in the area, Native American mounds were constructed in what is now Burlington. Although around 1830 a small Potawatomi village stood in what is now the Town of Burlington.
chart here
https://en.wikipedia.org/wiki/Burlington,_Wisconsin
topo showing the mounds
https://www.google.com/maps/place/B...16a313!8m2!3d42.6780726!4d-88.2762026!5m1!1e4
If the spot where the temp is being taken is in a low spot, then it all makes sense to me!
-John