Madison, Wisconsin — Freezing temperatures will develop overnight into Saturday morning, threatening vegetation and creating patchy slick spots on roads across Madison, Milwaukee, Janesville, Waukesha and Kenosha between 12 a.m. and 8 a.m. Saturday.
According to the National Weather Service in Milwaukee/Sullivan, a freeze warning covers most of southern Wisconsin during this period, with the coldest temperatures expected between 2 a.m. and 7 a.m. Inland areas will drop to 29°F to 32°F, while locations closer to Lake Michigan remain slightly warmer under a frost advisory.
Sub-freezing temperatures can kill sensitive plants within hours and may damage early-season crops. Frost forming on bridges and overpasses, especially along I-94 between Madison and Milwaukee and I-90 near Janesville, could create slick spots for early drivers. Low-lying rural areas and sheltered valleys west of Madison will cool fastest, while urban Milwaukee may see patchier frost but still reduced traction on elevated surfaces.
This is part of a broader system bringing unseasonably cold air into the Midwest following recent mild conditions, increasing stress on vegetation.
Residents should cover or bring in plants and use caution on early morning drives, particularly on bridges where frost develops first.
The most critical freeze and frost impacts will occur between 2 a.m. and 7 a.m. Saturday, when temperatures reach their lowest levels across southern Wisconsin.
