I'll have to pay attention to your temps this winter and compare.   

I do know that on most of the trips I took to DSM last winter, the daily high in DSM was often 20-30° warmer than at home.   The one day in late Feb I left DSM at noon and it was 55°F, when I got home at 4pm it was 22°F and that was the high for the day.

Its amazing what bare ground vs 2' of snow does.   You could watch the outside temp fall or climb on the car thermometer depending on if you were going into or out of the snow.     Going south on every trip last winter, Hwy 3 had considerably less snow than here, by Hwy 20 the ground was basically bare other than ditches.      As a result, even Sioux City was much warmer than here.