Scattered frost developed early this Thursday morning across many parts of the Chicago area – lowest temps in the low to mid 30s generally occurred along and west of the Fox River Valley – lowest reading was 31 degrees at Aurora/Sugar Grove.  

Mostly clear skies and light to calm winds allowed maximal radiational heat loss under the influence of a large high pressure centered over Lower Michigan. Closer in – the low temp at Chicago’s official O’Hare site was 44 degrees, Midway recorded a low of 46.

A Frost Advisory was in effect for Winnebago, Boone, McHenry, Ogle, Lee, DeKalb, and LaSalle counties until 7 AM.

Following is a list of lowest temperatures at area airport locations as of 7AM this morning:

Location/Lowest temp
Aurora/Sugar Grove…31
Pontiac….32
Freeport….33
Rochelle….33
DeKalb….35
Rockford….35
DuPage/West Chicago….36
Lansing….36
Joliet….36
Peru/Ottawa….37
Morris/Washburn….37
Waukegan….38
Romeoville/Lewis Univ….39
Kankakee….39
Palwaukee/Wheeling….41
O’Hare….44
Midway….46

NW Indiana
Rensselaer….34
Valparaiso….37
Gary….43

SE Wisconsin
Burlington/Lake Geneva….31
Kenosha….35
Janesville….36