The National Weather Service issued a Freeze Warning for much of southern Wisconsin and a Frost Advisory for counties along Lake Michigan, in effect from 1 a.m. to 9 a.m. on Saturday, Oct. 17.
Temperatures were expected to fall as low as 28 degrees in some inland communities early Saturday, with the coldest readings in the upper 20s and lower 30s away from the lake. Far western Racine and Kenosha counties were noted as more exposed because they sit farther inland.
Forecasters said the cold was enough to damage or kill sensitive vegetation and could affect unprotected outdoor plumbing. Frost can also form on exposed surfaces even when air temperatures stay just above freezing, because colder, denser air settles at ground level.
The chill followed a cold front moving through on Friday, with showers, blustery northwest winds gusting 30 to 40 mph, then clearing skies and lighter winds overnight. That clearing allowed heat to escape quickly, a process forecasters call radiational cooling.
Gardeners were advised to protect tender plants on Friday afternoon. The cold was expected to be brief, with highs recovering into the middle and upper 50s on Saturday afternoon, the lower 60s on Sunday, and the 60s through the following week, potentially near 70 by Wednesday.
