Big Cooldown to Follow Warm Stretch

After spending nearly a week on the warmer side of normal, a long stretch of cool weather is in store for the Stateline to end this month and kick off the next.

Between September 21^st and 26^th, high temperatures in Rockford exceeded the daily average with one of those days, the 25^th, hitting 80 degrees. However, as of Saturday evening, a potent cold front sits to the northwest of the Stateline with plans to move over the area on Sunday and initiate an unseasonably cool stretch of weather. This cold front is forecast to enter the northwestern Stateline in the early afternoon and last through the mid-evening. Its arrival time will likely mean an earlier than normal high temperature for Sunday which is forecast to be in the lower 70’s. This front will also bring with it a line of showers which is relieving news considering Saturday marks the 14^th consecutive day with no rainfall whatsoever in Rockford, something that the city hasn’t seen since September of 2017.

As winds shift to northwesterly following the passing of Sunday’s cold front, cold air continues to be fed into the Stateline and temperatures are forecast to only reach the lower 60’s on Monday. Another major contributor to the cooldown is a change in pattern for the jet stream. A large trough will form to the south of the Stateline which will pull some frigidly cold air into the Stateline from the north. The jet stream will also be moving rather fast through the week and the faster the jet stream is, the greater the influence it has on our weather, including temperatures.

Temperatures should level out from Monday through Wednesday staying in the lower 60’s. However, another cold front is expected to move through early Wednesday which should keep temperatures down in the middle 50’s for a high on Thursday. Highs in the 50’s are forecast to stick around through Saturday. Thursday and Friday night are expected to see low temperatures in the 30’s, something Rockford has not seen since this past April.

As of Saturday, there are no more 80’s in the foreseeable future. On average, the last 80° day of the season in Rockford is October 7^th though it’s come as early as September 10^th. The past five years haven’t given up on the 80’s until at least October 1^st. However, if this past Friday proves to be the last 80° day of the season, it will be the earliest since 2009 when it fell on September 18^th.