Just days after near-record heat, the National Weather Service issued both a Freeze Warning and a Frost Advisory for several counties across the Chicago area through Friday morning.
DeKalb, Kane and McHenry counties were all under the Freeze Warning, which warned of below-freezing temperatures in the upper 20s and low 30s.
Meanwhile, Cook, DuPage, Grundy, Kankakee, Kendall, LaSalle, Lake and Will counties in Illinois, plus Jasper, Lake and Newton counties in Indiana, as well as Kenosha County in Wisconsin, were all under the Frost Advisory, warning of temperatures falling into the 30s but still above freezing.
Both alerts took effect beginning at 1 a.m. Thursday and were scheduled to expire at 9 a.m. Friday, according to the NWS. Forecasters warned that outdoor plants may be damaged or killed if left uncovered outside.
Temperatures began to drop Wednesday after a day of showers and storms. Cooling into the 50s by Wednesday evening, the coldest air of the season will likely stick around for at least a week, lingering in Chicago over the next 10 days as temperatures remain well below average.
Thursday looks to be overcast and windy with a good portion of the day in the mid to upper 40s, reaching low 50s in the afternoon. Mostly clear and quite chilly conditions could see the first frost of the season overnight.
Friday will start mostly sunny and cold, and although clouds will build it will remains chilly through the afternoon with a few light scattered showers possible to the south.
The weekend stays cool throughout, with highs in the upper 40s to low 50s on Saturday and in the low to mid 50s Sunday.