Temperatures plunge, but fall's remarkable warmth isn't done yet

Fall Warmth By The Numbers:

If you're thinking to yourself, "Wow, it's been a warm fall so far," or even, "Are we actually in fall?", you're certainly not alone. This fall has been one for the record books. Since September 1, we've recorded 64 days with highs at or above 60°, setting a new record for most up until November 9th.  The previous record was 63 days back in 1963 and 1956. There's a great chance we'll add one more day to this impressive total before our next shot of cold air arrives. 

Mild Tuesday:

Today will be a copy-and-paste of yesterday's nice weather. With high pressure briefly building in behind today's frontal passage, expect abundant sunshine and highs in the low 60s. The main difference is the wind which will be out of the northwest and noticeably lighter as the cold front pulls away.  

 

Temperatures Plunge:

Tomorrow's clipper-like storm system will bring the chance for scattered sprinkles and showers starting around the morning commute, continuing into the early to mid afternoon hours. On the backside of the system, much colder air will wrap in and spill across the Great Lakes, setting the stage for a massive drop in daily highs and lows. Highs Wednesday will still manage to reach the low 50s, but will then tumble for both Thursday and Friday.  

Long-Range Warmth:

As we've seen throughout much of this fall, any shots of colder air have been short-lived, with temperatures quickly rebounding to above-average levels. That trend appears likely to continue. The latest outlooks from the Climate Prediction Center continue to favor a higher probability of above-average temperatures in the days leading to Thanksgiving. 

Rain chances return Wednesday to northern Illinois

Our dry skies will briefly come to an end mid-week as a quick moving low-pressure system is set to move across Illinois Wednesday, bringing a few showers and isolated thunderstorms for some.

For the rest of Monday night skies will remain mostly clear, although we will see a few clouds move in with the arrival of a cold front late in the evening. A light southerly breeze will limit how fast temperatures fall before the front arrives, which means our evening will remain in the low 40s. The cold front will come through dry, just shifting winds to the northwest Tuesday morning. Temperatures right before/around sunrise will likely fall back into the 30s thanks to some drier air moving in behind the front. Look for some patchy fog and frost early in the morning. With little air mass change behind the front temperatures on Tuesday will warm back into the upper 50s and low 60s, with a forecast high temperature of 61 degrees for Rockford. We should see a good amount of sunshine for the afternoon as well.

Cloud cover will move back in Tuesday night, though, ahead of an incoming low-pressure that'll move across central Illinois Wednesday afternoon. Ahead of the low moisture will spread north bringing scattered showers across northern Illinois. While there is a little bit of instability associated with the low, any big threat for thunder will remain to our south. Moisture with the low isn't significantly high but will be enough to bring some accumulating rainfall to the Stateline, but totals are expected to remain below a quarter of an inch.

The low will be quick to move out Wednesday evening, pulling in behind it an unseasonably cold air mass. This will push afternoon highs Thursday through at least Saturday into the 40s and overnight lows down into the 20s. While not too far from the average high (upper 40s), it'll be our coolest stretch of weather so far this fall season. But just like every cool snap it won't last. Temperatures are expected to warm back up into next week.

Enjoy the 60s while you can: Colder air arrives this week

Staying Mild:

If you loved the weather this past weekend, you'll enjoy the start of the new week as well. High pressure settling overhead will keep conditions quiet through much of the day, allowing for periods of sunshine and mild November temperatures. After a chilly start, we can expect temperatures to steadily climb to similar levels to Sunday, leaving us in the low 60s.

High pressure will remain parked nearby tomorrow, helping sunshine and pleasant conditions to stick around for another day across the area. 

Much like today and Sunday, we'll start off on the chilly side during the early morning hours before temperatures rebound nicely. Despite winds being out of the northwest, afternoon highs are expected to reach the low 60s once again.  

Midweek Storm System:

Changes arrive in the weather pattern on Wednesday as a clipper-like system dives southeast into the Great Lakes region. While this system will bring the chance for scattered showers during the day, especially for those along and south of I-88, the bigger story will be the colder air that follows in its wake.

 

Temperature Trend:

A reinforcing shot of chilly Canadian air will spill in for the latter half of the week, knocking temperatures back below-average. Highs are expected to reach the low 50s on Wednesday, then drop into the low 40s for Thursday and Friday. Compared to mid-November standards, this is 5° to 10° below average. Overnight lows will end up in the upper 20s. 

November chill sets up lake effect machine later this week

 The weather pattern will be rather quiet over the next couple of days with some milder afternoons featuring highs in the low 60s and overnight lows in the middle 30s to around 40. The only feature of note through Tuesday night will be some patches of frost or fog each night.

Our next weather system will arrive Wednesday along the leading edge of a strong push of cool Canadian air. This will bring scattered showers our direction through much of Wednesday and even early Thursday. All told, most will only see less than a couple tenths of an inch of rain.

The cooler air rushing in behind the system will set up a cold Northerly wind, kickstarting lake-effect precipitation on the Southern coasts of the Great Lakes. Some of this Canadian air may be just cold enough to mix in some pockets of snowflakes, which would mark the first of the season for some. Far Northern Illinois looks to be just far enough removed from the moisture Friday and Saturday, which should keep us dry compared to those East of us. But it will be cold and breezy with afternoon highs only in the middle 40s Thursday through Saturday.

I know we may not want to talk about "s-n-o-w" quite yet, but it will be here before we know it! On average, Rockford sees its first trace of snow around Halloween and the first 1" snowfall around early December. The earliest measurable snow in Rockford's history was October 12th, 1909. One year ago today brought Rockford's first snow of the 2025-26 winter season, with 1.2" falling at the airport. So, at the very least, this season's first snow will be a bit later compared to last year.

Mild few afternoons, fall chill returns later in the week

 While it will be a bit breezy Sunday, temperatures will still rise near the 60-degree mark. Similar numbers are expected with high pressure overhead Monday and plentiful sunshine Tuesday. Overnight lows may be chilly, particularly Sunday night. But overall, temperatures will be running a few degrees above what is typical for this time of year, at least for a couple days.

Our next push of cooler Canadian air will arrive with a passing weather system Wednesday and Thursday. This will bring some pockets of light showers our way, then some lake effect precipitation across the Eastern Great Lakes before the weekend. While we will likely be far too dry for anything here, parts of Northern Indiana, Michigan, and Ohio may see some of the white and fluffy stuff. Our main impact will be the fall chill, as highs return to the 40s to close out the week.

Widespread frost tonight, elevated surfaces could become slick

 Friday was a chilly day in the Stateline despite the abundant sunshine. The afternoon high of 49 degrees marked the coolest high since we saw only 44 degrees April 7th, over 200 days ago!

A clear sky tonight will work to enhance radiational cooling, where the solar radiation built up from the day escapes into space. This will lead to a cold night with overnight lows in the upper 20s! A bit of surface moisture will likely allow for a widespread frost to develop. A few elevated surfaces (such as decks or balconies) may become slick! I do not expect any issues to roadways, however.

This weekend will start on a cool note again, as afternoon highs will only rebound to the low 50s Saturday afternoon, but near 60 on Sunday. A few passing upper level clouds will not block out too much sunshine. While not as cold, overnight lows will remain in the 30s the couple nights to follow.

Stateline weather whiplash: 20s tonight, near 60 Sunday

Mild Nights No More:

With how mild this fall has been, freezing overnight temperatures have been hard to come by. In fact, we here in Rockford have only recorded one morning low at or below freezing so far this season. 

That all changes tonight. After a partly cloudy Friday with afternoon highs in the upper 40s, temperatures will tumble quickly after sunset as colder air settles into northern Illinois and southern Wisconsin. Low temperatures are expected to drop into the upper 20s, making it the coldest night of the season thus far and setting the stage for some frost by sunrise Saturday morning. Those with any remaining sensitive plants outdoors will want to take the necessary precautions before heading to bed this evening. 

Mild Weekend:

Fortunately, the taste of winter won't stick around for long. While temperatures plunge into the upper 20s tonight, milder air quickly returns for the rest of the weekend. Saturday will feature mainly sunny skies with afternoon highs in the low 50s. 

Temperatures will settle into the low 30s by Sunday morning, allowing another round of patchy frost to be possible, particularly in areas that dip closer to the freezing mark. After a chilly start, temperatures rebound nicely by Sunday afternoon, with highs returning to around the 60-degree mark. This mild stretch continues into next week as we hold onto ridging and a southwesterly wind.