First Frost Potential for Southern Wisconsin (Updated 10:00 am Sat)

Light surface winds and clear skies allowed temperaures to fall into the 30s across much of northern and central Wisconsin the last few mornings. A few locations even dropped into the 20s. The coldest official temperature measured in Wisconsin Saturday morning was 27 degrees at the Ashland Airport in northern Wisconsin. Satuday morning was slightly warmer than Thursday and Friday mornings. Across south central and southeast Wisconsin, some of the coldest temperatures reported were 38 degrees at from our cooperative observers at Holy Hill and Slinger.

Here is the link to the daily high and low temperature listing as well as 24 hour precipitation for across Wisconsin.

Mostly clear skies and lighter surface winds are expected again tonight across south central and southeast Wisconsin. Below is the forecast low temperatures for tonight into early Saturday:

The cool conditions are expected to persist across southern Wisconsin into the weekend. However overnight temperatures are expected to remain mostly in the upper 30s to middle 40s at night across inland areas, and in the middle 40s to middle 50s by Lake Michigan. Hence the threat for frost will be very low during the late night and early morning.

The first week of October tends to be the average period during Autumn when the first 32 degree reading occurs across most of southern Wisconsin. Take a look at the below graphic which illustrates the median 10 day period for the first 32 degree temperature across Wisconsin and the region:

For interest, here are a pair of graphics illustrating the earliest and latest 32 degree readings across Wisconsin and the region:

Kavinsky/Herzog
National Weather Service - Milwaukee/Sullivan