Big Changes to Come Following Tonight’s Cold Frontal Passage


Scorching Sunday:

The last weekend of summer went out with a bang as warm southerly winds and plenty of sunshine brought our afternoon highs into the low 90s. In fact, Sunday’s high of 93-degrees at the Rockford Airport tied for the warmest September 19th on record, now tied with 1925, 1947, and 1948. Although not as hot, Monday remains warm ahead of a strong cold front that will help usher in big-changes by the fall equinox.

Few Morning Showers:

Believe it or not, the remnants of tropical storm Nicholas will be a big part of today’s forecast. As the moisture associated with it slowly creeps northward, Monday begins with a chance for a few sprinkles and light showers. 

Otherwise, we remain dry and breezy into the afternoon, with gusty winds becoming a concern for those traveling late in the day. A stout southerly to southwesterly wind, which could gust to around 25-30 mph at times, will help push highs into the low to mid 80s. Winds remain out of the southwest but quickly will change to the northwest as a strong fall cold front slides through overnight. Along with this frontal passage does come the potential for strong to severe thunderstorms.

Overnight Storms:

In the latest outlook, the Storm Prediction Center has placed half the Stateline under a Slight Risk (level 2 of 5) for severe weather, with the eastern half under a Marginal Risk ( a category below). Storm looks to fire up along this frontal boundary late in the afternoon in central Iowa, and track eastward as we head into tonight. While it seems this line of showers and thunderstorms will be in a weakening phase on approach, gusty winds and heavy rainfall will be the primary threats. A few sprinkles may last into early Tuesday morning, with conditions drying out but remaining breezy into the afternoon.

Fall’s Moving In:

Winds behind tonight’s frontal passage will turn to the north-northwest, allowing a much cooler, more fall-like air-mass for the days to come. Highs look to drop significantly from the low 80s today to the low 70s by Tuesday afternoon. And if that wasn’t cool enough, we see our daily highs drop even further as we head into Wednesday. 

You would have to all the way back to July 8th to find the last time Rockford observed a high in the 60s. Well, with this much cooler air-mass still sitting overhead, we may see the 60s return both Wednesday and Thursday. Along with cooler days comes cooler nights, as overnight lows moving forward look to fall into the 40s. A few isolated areas may flirt with the upper 30s early Thursday morning. Prepare yourselves, fall is coming! 

Copyright 2021 Nexstar Media Inc. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.