The first Frost Advisory of the fall season has been issued for southern Wisconsin and most of northern Illinois beginning late Sunday night, lasting through 9am Monday.
Skies have been mostly cloudy for much of Sunday afternoon limiting how far temperatures were able to climb. Highs throughout the region made it into the middle 50s, with the upper 50s southwest of Rockford where the sun was able to peek through a little longer during the day. As drier air wraps in throughout the evening cloud cover should continue to thin out. This will allow temperatures to gradually drop down into the 30s. Low to mid 30s are possible in some of the low-lying areas, and areas that experience clear skies a little longer during the night. Widespread, heavy frost is not expected at this time.
It is possible that the clouds don’t clear fast enough during the night. If that occurs, then the frost potential would be lower. We may actually have a better chance for frost development Monday night under mostly clear skies and light winds.
While it may seem early, we’re actually not too far off from when we typically experience our first fall freeze. That usually occurs within the first week and a half of October, with a hard freezing occurring a week later. However, temperatures just a week ago were in the middle 80s so highs in the 50s feel quite a bit colder!