Wednesday afternoon rainfall update

 

Rainfall totals across the Stateline range from a few tenths of an inch north of the state line to just over an inch along and south of I-88. The heavier rain from the morning took a little break early afternoon, but steady showers continue to fall south of Rockford.

Over the next few hours scattered showers will remain from Iowa across northern Illinois, leaving most of southern Wisconsin dry, but foggy. Through the late evening the rain will slowly begin to pull

back north as several little upper-level disturbances move through, along with a slight increase in moisture and low-level jet. This will allow for some heavier rain to develop during the overnight and lasting through most of Thursday morning. Flood Watches have been issued for Carroll and Whiteside counties until late Thursday night.

Temperatures will hold steady in the low to mid 60s through much of the night, rising only a few degrees Thursday afternoon. As a cold front moves across southern Wisconsin and into northern Illinois during the afternoon it'll take the heaviest rain south with it, with more scattered showers lasting into Thursday evening.  An additional 1-2 inches of rainfall will be likely between what comes down Wednesday evening through Thursday evening.

  

Another soaking rain on the way for northern Illinois

Rain Chances Return:

Rain has made its return to the Stateline, and it looks like it's here to stay into October. A steady influx of moisture from the southern and central plains will keep showers in the forecast, with periods of heavy rainfall possible at times. 

 

Timing Out the Rain:

The heaviest rainfall today is expected to fall before mid-morning, so before 9-10AM. You'll definitely want the umbrellas, rain gear, and windshield wipers ready for the morning commute. While today's rain is expected to decrease in coverage towards midday and for the afternoon, don't put the rain gear away. Keep it on hand as scattered showers will be a possibility for the second half of the day. 

Showers will remain scattered through the overnight hours, though an occasional heavy downpour or two cannot be ruled out. Another, more widespread round of rain is expected to move through on Thursday as our cold front prepares to push through. Coverage will increase through the morning, with some of the steadiest and heaviest rain looking to occur during the late-morning and early-afternoon hours. So like today, the umbrella will be a must.

Drying Out for the Weekend: 

Rain showers may linger through the first few hours of Friday, but that will also mark the beginning of a transition to a drier and quieter weather pattern. As the system responsible for the midweek rainfall shifts to our east, drier air will gradually work its way into the Stateline, bringing an end to the extended stretch of wet weather. Afternoon highs, thanks to the cold front that pushes through late Thursday, will fall into the mid to upper 60s for the weekend. 

Rainfall projections have remained fairly consistent over the past few days, with most locations expected to pick up between 1" to 2". As of this morning, this September ranks as the 19th wettest on record for the Rockford, but there's a good chance that ranking will climb with what passes through today. 

Temperatures reach 80 degrees in northern Illinois Tuesday afternoon

 It has been another spectacular late September afternoon! After chilly start Tuesday morning, afternoon temperatures warmed nicely throughout the Stateline reaching the upper 70s and low 80s! The average high should be right around 70 degrees. But the warmth doesn't last and in just a short 12 hours it'll look, and feel, quite a bit different outside.

Clouds will continue to thicken up through the evening which will slow just how fast temperatures

fall through the night. Overnight lows will remain right around 60 degrees. Skies will remain dry through Midnight, and likely through 2am/3am, but light rain showers will move in from west to east with a heavier rainfall expected through sunrise Wednesday. Temperatures will have a hard time warming much above 70 degrees Wednesday afternoon, despite the southwesterly wind. Following a strong cold front Thursday night high pressure settles in for the upcoming weekend leaving temperatures in the 60s.

Umbrellas required: Soaking rain chances ahead of fall cooldown

What's Ahead?:

Patchy dense fog may once again develop across the Stateline early this morning, potentially leading to reduced visibility for those traveling. Any fog or low clouds should gradually lift as we approach the mid-morning hours, but our attention then turns to our next storm system. Moisture will continue to spill in Tuesday evening into Tuesday night, allowing rain to become likely by Wednesday morning. 

Timing Out The Rain:

Scattered showers and periods of steady/heavy rain are expected both Wednesday and Thursday as the cold front approaches from the west. While severe weather is unlikely during this stretch, a rumble of thunder or two cannot be ruled out. 

Current forecast guidance continues to point towards the heaviest rain arriving Wednesday morning, with another round pushing in as we inch closer to midday Thursday and into Thursday afternoon. There is also some indication that tropical moisture could become involved with this incoming rain. The reason why?  The jet stream is expected to pick up the remnants of former major hurricane Polo and swing it in our general direction, helping boost rainfall efficiency and totals across portions of the Midwest. 

It's safe to say you'll want to keep an umbrella handy both Wednesday and Thursday. Most locations could receive more than an inch of rain by the time this system exits into the Great Lakes, while isolated areas may pick up as much as 2"+ where the heavies bands of rain persist. While the exact amounts will continue to be refined over the next 12 to 18 hours, confidence is growing for another soaking rain. 

Beautiful late September afternoon

 

After a rather chilly and foggy start Monday morning temperatures were able to warm nicely for the afternoon, reaching a high of 77 degrees in Rockford. While not too far above the average high of 71, it has been nice to have some warmth following the cooler and wet weather a week ago.

High pressure will still hold strong through the night which will help keep our skies clear, allowing temperatures to once again fall back into the upper

40s. Similar to Monday morning areas of fog are likely to develop early Tuesday, with some locally dense fog possible overnight. Clouds will be on the increase through the afternoon and evening Tuesday, but despite that temperatures are expected to warm back into the mid-70s. Skies will cloud over Tuesday night with temperatures holding right around 60 degrees. Rain will then move in during the day Wednesday, with some heavy rainfall possible through Thursday night.

Pleasant start to the week before a multi-day rain threat returns

Patchy Morning Fog:

Some patchy dense fog is beginning to develop just before the start of the morning commute. Morning meteorologist Owen Szarley mentioned that the fog was particularly dense in DeKalb County during his drive into the station. While no dense fog advisory has been issued at this time, those traveling should be prepared for fluctuations in visibility. Allow for a little extra time, keep your low-beams on, and be prepared for pockets of thick fog. 

Pleasant Monday:

High pressure anchored over the western Great Lakes will make for a pleasant start to the week. Any fog or low clouds lingering from this morning will gradually lift, giving way to a mix of clouds and sun. Afternoon highs will end up back  into the low 70s, a touch above late-September standards.  

 

More Fog Potential:

High pressure will also promote a very dry and quiet atmosphere overnight into Tuesday. Combined with a light easterly to southeasterly wind and mainly clear skies, that could set the stage for another round of fog during the early morning hours Tuesday. Currently, guidance suggests the best chance for travel impacts will be east of I-39, though areas outside of that area could still see localized fog. 

Rain Chances Increase:

Tuesday will remain dry through the daylight hours, but changes will begin to take shape as moisture will gradually increase across the region. Expect clouds to build through the afternoon and evening, with skies becoming mostly cloudy late. Rain chances will ramp up shortly after midnight as the next disturbance approaches from the west. This will mark the start of a more active weather pattern, with steady/heavy rain being a possibility through Thursday.   

Second half of this week more active with frequent rain showers

 Very pleasant, but warm fall-like weather has been the trend this weekend and will continue to be for the first half of the week. But a pattern change is on the way for the second half of the week, including a potential for some pockets of heavy rainfall.

There are still a number of moving parts to the forecast because of a complicated upper-level pattern involving an outgoing Nor'easter to the East and remnants from tropical systems to the West. Because of this, there are some uncertainties that remain. First off, we are confident in the more active pattern as a whole with increasing moisture Tuesday night and Wednesday, with pockets of steady or heavy rain through at least Thursday. But the exact placement of the cold front each day and where the heaviest rain will set up is still in question.

The system has been trending to arrive later and later over the last few days, resulting in a now dry forecast through at least Tuesday evening. Initial showers may not even arrive until Wednesday morning with drier air still in place ahead of the cold front.

But the slow-moving nature of the front will allow moisture to build in along it, producing pockets of steady to heavy rain particularly Wednesday night through Thursday. A few locations may be able to see more than an inch of rainfall, especially if the cold front stalls out overnight. Showers will eventually exit the area as higher pressure arrives from the Northwest, bringing an end to the rain by Friday afternoon. Cooler air will then follow with afternoon highs in the mid-60s next weekend.

Pleasant, fall-like conditions into early week

 Large-scale blocking will prevent much change in the weather pattern over the coming days, with more sunshine and pleasant fall-like weather continuing. The strong Nor'easter over the Atlantic Coast will keep this block in place through the next few days, limiting daily changes in the weather conditions.

We have a nearly a copy and paste forecast over the next few days as a result, with afternoon highs in the low 70s and overnight lows in the upper 40s to low 50s. A few patches of fog may be possible each night, but we will stay dry through Tuesday afternoon. Later in the evening and into next week will bring a more active pattern with more frequent chances for rain.

Weekend mostly dry, active pattern sets up again next week

 Moisture and dry air continue to play tug-of-war over the region this weekend, but drier air seems to win over locally. While an isolated sprinkle or two may be possible from time to time, most of Northern Illinois will remain dry this weekend with highs near 70 and lows near 50. Better chances for light showers will be possible to our West, mainly across Iowa.

A much more active pattern will then develop toward the middle and end of next week. A series of low pressure systems will each bring more widespread rain chances with it, including the potential for some locally heavy rainfall. The first cold front will slide over the region Tuesday evening and overnight, with at least scattered showers.

That front will then stall down to our South as another low pressure system lifts the moisture back our direction later in the week, continuing the active streak. The exact placement of this front is still in question as to where the heaviest rain may fall, but we do look to remain rather active through the end of the week. Widespread rain with a few embedded thunderstorms could be possible Tuesday evening through at least Friday.

A perfect balance of light: The equilux explained

What is the Equilux?:

While the fall equinox marks the official start of the astronomical autumn season, it is not the day where we receive exactly 12 hours of daylight and 12 hours of darkness. That distinction belongs to what's known as the equilux, which means "equal light". 

The equilux is the day when sunrise and sunset are separated by almost exactly 12 hours, resulting in an equal balance of day and night. Because of the Sun's size and the way Earth's atmosphere bends sunlight, the equinox and equilux do not occur on the same day. For instance, Rockford's spring equilux took place on March 17th, while the autumn equilux is scheduled to occur tomorrow, September 26th. Our sunrise is at 6:47AM and sunset is at 6:48PM, giving that equal split in day and night. Once the equilux passes, daylight hours continue to shrink, allowing nights to grow longer. 

Dry air gains ground as rain chances across northern Illinois fade

Shower Chance Early:

Over the next few days, we'll continue to watch a bit of tug-of-war unfold across the region as dry air anchored over the Great Lakes battles increasing moisture trying to push in from the west. Right now, moisture is winning out, leading to sprinkles, and even an isolated shower to start the day.  

Fortunately, any rainfall over northern Illinois will remain light, with no heavy rain expected. In fact, the best chance for any rain will be during the morning hours, primarily before 9-10AM. After that, dry air will take over as high pressure inches west, allowing conditions to gradually dry out and skies to transition to a mix of clouds and sun. Temperatures remain on the cool side, topping out in the upper 60s, while a light easterly wind keeps the early-fall feel. 

Dry Weekend Ahead:

High pressure will continue to inch closer to the area through the weekend, allowing dry air over the Great Lakes to win out. As a result, rain chances remain slim and very limited, with Sunday presenting the only weekend opportunity for rain in the form of a brief sprinkle. Otherwise, the persistent push of dry air from the east will make it difficult for moisture to successful spill into the region. Temperatures remain comfortable, hovering around 70 degrees. 

 

 

Active pattern brings more frequent rain chances to close out September

 After a very wet weekend, the last few days had been a nice break from the rain. But another active pattern will bring us better chances for rain again toward the middle and end of next week, right in time for the flip of the calendar into October.

It all starts with a shift in the upper level pattern over the next week. This coming weekend, blocking between high pressure over the Great Lakes and a strong Nor'easter will keep rain chances to a minimum. But once that pattern releases, a stronger jet will draw more frequent low-pressure systems our direction, beginning Tuesday and Wednesday.

The stronger Southwest direction to the winds near the surface and aloft will work to draw in that much more moisture. As a result, it will be much more abundant compared to this weekend, resulting in better coverage and intensity of rain. Rain chances will begin Tuesday afternoon and could continue on and off through the end of the week. A few thunderstorms may also be possible, with stronger dynamics in place.

The active pattern may continue into the first few days of October as well. The Climate Prediction Center gives Northern Illinois around a 50-60% chance to see above average precipitation between September 30th and October 4th, likely owed to the more active jet stream mentioned above. Looking further ahead to mid-October, we typically get at least one or two shots of chilly fall-like weather, with the first potentially set to arrive around October 5th-8th.

Weather pattern blocked into the weekend

 

It has been nice to get a break from the thick overcast skies the last several days, allowing a little more sunshine to help warm temperatures into the low 70s both Wednesday and Thursday. But the clouds have moved back in Thursday evening which will leave our skies cloudy through the night.

Temperatures will be slow to fall this evening, dropping only into the upper 50s overnight. Light rain well to our west will slowly inch close to the Stateline Thursday night and Friday morning but will be battling - at least initially - drier air from high pressure over the eastern Great Lakes. Early Friday - after 3am or 4am - a few sprinkles and/or light rain showers may start to move into northwest Illinois, spreading east through daybreak. The highest rainfall totals are expected to remain west of the Mississippi River with enough rain to wet the sidewalks locally, adding up to perhaps a tenth of an inch at most. A few sprinkles may last through Noon, but throughout the afternoon the cloud cover should begin to break thanks to drier air settling in from the east. This will help clear skies Friday night allowing temperatures to fall around 50 degrees Saturday morning.

High pressure will hold strong through the weekend keeping the highest moisture to our west. This will result in a mostly dry, and comfortable, weekend with temperatures in the upper 60s and low 70s.

This blocking pattern is the result of what will be a strong low-pressure system developing off the east coast this weekend. Through Saturday afternoon the center of the low will remain just off the coast, but by the evening it'll begin to shift back west. This will help hold high pressure in place through Monday afternoon across the Great Lakes. 

There could, though, be a few showers that try to sneak into our air space late Saturday night and Sunday as an upper-level disturbance moves through the Upper Midwest. But with the drier air in place, any rain is expected to remain on the lighter side.

  

Pleasant days, limited rain chances ahead

Pleasant Thursday:

Yesterday provided a welcome break from the recent stretch of heavy rainfall across the Stateline. While a few clouds drifted overhead at times, temperatures remained comfortable, topping out in the upper 60s and low 70s, making for a pleasant start to the fall season. More of the same weather is on tap today as high pressure remains firmly in control across the Great Lakes and southeastern Canada. 

Shower Late Tonight:

High pressure will keep our weather dry through the night, but forecast models continue to show a subtle increase in moisture occurring after midnight. That may be just enough to spark an isolated shower in a few spots, though some of the precipitation could fall as virga, which is precipitation that evaporates before reaching the surface due to a layer of dry air that is situated beneath the cloud base.   

Dry End to the Week:

The best chance for any precipitation will come before 9 to 10AM Friday as a weak disturbance slides through the Stateline. Even then, rainfall looks spotty, with totals remaining under 0.10". Most locations closer to I-39 will remain dry with forecast trends pushing the better chance for measurable rain to the west of the Mississippi River. Clouds will hang tight, though a few peeks of sun cannot be ruled out with highs topping out in the upper 60s.

 

 

Cool pattern with limited rain chances through the weekend

 If it feels like we haven't seen the sun in a long time, the data backs it up. Rockford has not seen under 50% cloud cover in over a week and a half! There was a little bit of sunshine Wednesday, but not enough to break the streak of mostly cloudy days.

Not much broad sunshine expected in the coming days, despite higher pressure remaining nearby. But the cooler East wind sticks around, blocking most of the abundant moisture from reaching our area. We may see a few isolated showers or even sprinkles Friday and Saturday, but many will stay dry with high pressure limiting precipitation. Further East, a strong low pressure system will bring coastal flooding and heavy rainfall to parts of the East Coast.

Eventually, the pattern breaks down and sends a stronger cold front our direction toward the middle of next week. This also comes with broader chances for rainfall, as hinted by the Climate Prediction Center's outlook. Expect a wetter pattern toward early October with more frequent chances for precipitation.

Autumn arrives with a break in the rain across northern Illinois

Very Wet September:

Yesterday's rainfall may not have been a blockbuster by any means, but every little bit counts. Rockford picked up an additional .21" of rain on Tuesday, pushing the monthly rainfall total to 6.43". That puts September 2026 ranked among the top 10 wettest on record through the 22nd of the month. To compare, Rockford typically sees 2.79" of rain from the 1st to the 22nd, meaning we've received more than double our average rainfall so far. 

Break from the Rain:

Rain chances will become much more limited over the next few days as high pressure settles over the northern Great Lakes. While a brief sprinkle can't be ruled out today, most of the day should remain dry with a mix of clouds and sun. Similar conditions are expected Thursday, with dry weather likely lingering into week's end. With a cooler fall air mass in place, temperatures will end up just below late-September standards, in the upper 60s each day.  
   

Fall arrives with a chilly start across northern Illinois

Fall Begins Today:

Astronomical fall officially begins today with the arrival of the autumnal equinox. This mark the moment when the sun is positioned directly over the Earth's equator, resulting in nearly equal amounts of daylight to darkness. 

  

Sunrise & Sunset: 

For instance, today's sunrise is scheduled to occur at 6:43AM, while sunset is set for 6:53PM, giving us roughly 12 hours and 10 minutes of daylight. From this point forward, daylight will continue to decrease as the sun takes a lower path across the sky, with sunset arriving a little earlier with each passing evening until we reach the winter solstice, the shortest day of the calendar year. 

Cool to Start Fall:

While summer-like warmth can still make an appearance in the weeks ahead, the equinox signals the official transition into the fall season, bringing shorter days, longer nights, and a steady march towards cooler temperatures.  

Typically, the Rockford Airport sees average highs near 73° near the start of the fall season, but temperatures over the next few days will run below that mark. A cool east to northeast breeze, abundant cloud cover, and lingering low-level moisture will keep high temperatures suppressed, with many locales struggling to get out of the low 60s this afternoon. Temperatures get slightly warmer and closer to average for tomorrow and Thursday, climbing into the upper 60s.    

Last day of summer stays cool and cloudy

Rainfall Check:

The soaking rains we've picked up the past week have helped make this one of the wettest Septembers on record for the Rockford area. As of this morning, the monthly rainfall total stands at 6.14", ranking this September as the 9th wettest through the first 20 days of the month. While it doesn't top the charts in that specific category, the bulk of that rainfall has fallen in just the last week. From September 14th to the 20th, Rockford picked up 5.83" of rain, meaning nearly all of this month's total has been observed during that 7-day stretch. Fortunately, the weather pattern settles down this week, with rain chances becoming much more isolated and less frequent compared to the rounds of rain and downpours we've recently seen here in the Stateline. 

Fall Begins Tuesday:

Cloud cover will likely hang tight for the final day of summer, and with plenty of low-level moisture still in place, drizzle or a few light showers can't be rule out at times. As a result, temperatures will remain cool, with highs landing in the low 60s. The breeze that we see out of the northeast throughout the day will also help limit our temperature climb. 

Tomorrow marks the official start of fall, as the fall equinox is scheduled to occur at 7:05PM CDT. During the fall equinox, the Earth's axis is tilted neither toward nor away from the sun. As a result, the sun shines directly over the equator, allowing nearly equal amount of daylight and darkness. Climatologically, September 22nd features an average high of 73 degrees and an average low of 51 degrees, serving as a reminder that cooler days and crisp autumn nights will become more common. 

For the first day of fall, afternoon highs will remain below average in the low 60s. The best chance for any rain will be before 9AM, with skies turning partly cloudy for the afternoon. High pressure from there should keep us dry into the middle and second half of the work week, though a slim chance for a sprinkle or shower remains for Wednesday.