Even June 2008 had some hot weather... SEA had 2 days over 90 during the last week. It probably can't stay this extreme on the cold side for much longer.
Use data from nearby PWS in aggregate from both Wundermap and MODIS. Check for a DOT and USF weather station as well. I’m assuming this has something to do with frozen surfaces, so you also should have your friend cross reference those temps with shadowing because a 39° air temp in the sun can still be 30° at the surface in a spot that would have been shaded all day.