The strongest low pressure system to affect the Midwest this fall will move through the area Friday and Saturday. It will begin to mature by Thursday morning. And, as that happens, a warm front will surge north of the Stateline. That will allow strong and warm southerly winds to usher into the region Thursday. Those winds should support high temperatures topping out in the middle and upper 60's Thursday afternoon. However, it would not surprising to see highs of 70° scattered across northern Illinois. It will all depend on how much sunshine prevails through the day. If sunshine sticks around all day, low 70's are certainly not impossible.
For Rockford, the current forecast is calling for a high temperatures of 70° Thursday afternoon. If we see that, we will only end up 3° shy of a record high temperature for the day! Be sure to enjoy that warmth because it may very well be the last time we flirt with 70° until 2017! In addition, a big-time drop in temperatures is expected behind the frontal boundary for the weekend. That is why we encourage you to get out and do outdoor activities this week! That front will send temperatures from near 70° on Thursday to only 40° on Saturday.
Beyond Saturday, we may struggle to get out of the 30's on both Sunday and Monday! In other words, get ready for the coldest air of the season thus far. And it's not just here in Illinois and Wisconsin. Locations from Kansas City to Bismarck to the entire of state of Michigan will see their coldest air of the fall. Not only that, but several inches of snow and blizzard-like conditions are expected across the Northern Plains and Upper Midwest! The season's are definitely changing.