Slow-moving system brings much-needed rain back to northern Illinois

Rain Chances Return:

Following an exceptionally dry July and worsening drought conditions across northern Illinois and southern Wisconsin, much-needed rain chances are set to make a return to the Stateline. A slow-moving area of low pressure will drift across the Midwest before gradually tracking across Illinois Saturday, bringing periods of showers, possibly heavy, and thunderstorms back into the forecast.  

Heavy Rain Possible:

The first half of the day is expected to remain dry, though clouds will gradually increase ahead of the approaching storm system. 

Rain chances will begin to rise as we head toward midday and the early afternoon, with scattered showers and a few thunderstorms developing across the region. Those scattered rain showers will likely linger into the evening hours before a second, more widespread round arrives as we head into the overnight hours as the surface low slides in. If you are heading to any events this evening including City Market, Festa Italiana, or the Ogle County Fair, have an umbrella on hand. 

While severe weather is not anticipated near the Illinois/Wisconsin border, a few stronger storms may drift into our southwestern areas. That is where you will find a level 1 Marginal Risk for isolated strong to severe storms, with damaging winds being the main concern. And again, heavy downpours/flash flooding will also be a concern. Further to the southwest is where the highest severe potential (level 2 of 5 Slight Risk) resides where all severe hazards, including a tornado or two, will be possible. 

Rainfall Potential:

The tougher part of the forecast, rainfall totals. The reason why, forecast models continue to struggle with the exact placement of the center of the low, which determines where the heaviest bands of rain will set up. Right now, most will likely see 1-2" of rain, though it isn't out of the question for there to be very localized amounts above 2". The last time Rockford observed 2+" of rain, 49 days ago on June 11th, the same day of the central Illinois tornadoes.   

Limited July rainfall results in worsening drought conditions

 Rainfall has been especially hard to come by over the last few weeks, resulting in spreading drought conditions across the Stateline. We started July on a wet note, with 2.35" of rain coming down in the first 5 days of the month. But since then, only 0.18" of rain has fallen, with no measurable rain since July 20th. That puts our monthly rainfall at 2.53" of rain, over an inch below normal through the 30th.

The lack of rainfall has not been exclusive to Rockford either. Much of the Stateline has not seen abundant rain this month, with much of the area North of Highway 20 seeing less than 2" of rain in the last 30 days. Compared to typical, most areas have only seen half of the rainfall that is typically expected during that time.

And the dry stretch over the last few weeks has resulted in developing drought conditions, with nearly the entire Stateline now experiencing at least "abnormally dry" conditions, with moderate drought across parts of Northern Illinois, including much of Winnebago County. Thankfully, a soaking rainfall is likely Friday night into Saturday, which will eat into the rainfall deficit quite a bit.

Widespread rain becoming likely Friday night

 Written By: First Warn Weather Intern Patrick Murray

While most of the Stateline currently sits in the "abnormally dry" drought category, a change is likely coming this weekend. Widespread rain chances enter the forecast as early as late Friday morning and look to last through Saturday morning.

A broad area of low pressure will move into the Stateline over the course of the next few days, bringing with it widespread rain chances and some gusty winds at times. Rain looks to start as early as late Friday morning. We will have some dry air in place thanks to a departing area of high pressure that the initial rain will have to work to overcome, so I do think the start of the rain could be closer towards the noon hour.

Expect scattered to widespread showers and perhaps a few rumbles of thunder throughout Friday as this area of low pressure slides east just to the south of the area. Not expecting the entire day to be a complete washout, but much of the day Friday will see rain.

Overnight Friday, more widespread rainfall is expected. This will last into Saturday morning, before the area of low pressure finally pushes east and we begin to dry out.

The tougher part of the forecast comes when looking at rain totals. Models are struggling with the exact placement of the center of pressure, which determines where the heaviest bands of rain will set up. Right now, much of the Stateline will likely see 1-2" of rain, while areas south of I-88 have the best chance at seeing 2+" of rain.

In short, rain chances increase as Friday goes on, with widespread rainfall lasting through Saturday morning, before finally wrapping up Saturday afternoon. Drier conditions look to enter the Stateline for the first half of next week.

Weekend plans? Keep the umbrella handy as rain chances increase

Dry, Warm Thursday:

Weather headlines across northern Illinois have been fairly quiet over the last few days, and with an area of high pressure still in close proximity to the region, that trend is expected to continue today. Expect a mix of clouds and sun this afternoon, with temperatures climbing into the upper 80s. Humidity levels will be slightly higher as dew point temperatures should wind up back in the mid to upper 60s.  

Rain Returns Friday:

Changes will begin to arrive overnight as this quiet and stable weather pattern breaks down. Clouds will gradually increase through the night as a ridge of high pressure to our west weakens, allowing a system to shift closer to the Stateline. 

  

As a result, the chance for rain will go up as we get into the late-morning hours Friday. Some of this rain could produce locally heavy rainfall thanks to the amount of moisture surging northward. Now, we will need to see where this storm system tracks because that would ultimately pin down who gets a widespread and soaking rainfall. Rain is expected to stay put on a scattered basis through Friday afternoon and well into Friday night. 

There's a good chance shower chances linger trough the first half of Saturday as this storm system drifts into southern Illinois. When it comes to rainfall amounts, be sure to check back later this evening as we still have time for the forecast to adjust. That said, confidence has slightly increased in a wetter outcome over the past 24 hours, with precipitation totals trending upward. Currently, the Weather Prediction Center places the axis of heaviest rainfall across eastern Iowa and northwest Illinois. 

Festa Italiana 2026:

Those heading out to Day 3 of the Ogle County Fair and opening day of Festa Italiana will want to keep an umbrella handy and stay up to date on the forecast and event schedules. Periods of showers could impact outdoor activities at times Saturday, though it won't be a washout from start to finish. The good news is that as the system pulls away, rain chances should diminish later Saturday into Sunday, paving the way for drier conditions as both events wrap up. 

Rain returns Friday afternoon

 

Our skies have been dry for quite some time for the majority of the Stateline. While we've had some rainfall here and there, the last one-inch rainfall total came back on the 4th of July with a few storms that moved across northern Illinois and southern Wisconsin. And while there have been some areas that have received rainfall since then, a lot of the precipitation has been hit or miss and not widespread. But that could all change Friday with the arrival of low pressure during the afternoon and evening.

Normally I don't get too excited when our forecast models are showing the potential for a lot of rain when we are in the middle of a dry stretch or several days out. More often than not, the precipitation amounts end up trending downward the closer we get to the rain event. And because of that I'm still not completely confident that the entire area will receive beneficial rainfall, but the odds are a little higher for at least *some of the region to experience the rain.

For the remainder of Wednesday evening, we'll see clear skies and calm conditions. High pressure over the Great Lakes means another cool night with temperatures on either side of 60 degrees Thursday morning. We may, though, see some patchy fog develop during the overnight. Thursday will start off clear, but clouds will slowly increase during the afternoon and evening, leading to mostly cloudy skies Thursday night. Low pressure developing to our northwest during the day Thursday will slide to our south Friday and Friday night, nearing southern Illinois Saturday morning. The track of the low would favor areas to the north of it for receiving heavier rainfall as this is where the stronger forcing resides within the low. But one of the factors that could put a 'wrench' in the higher rainfall potential would be the heaviest rain shifting south towards where the storms would be. If that occurs it would lower our chance for a good widespread soaking rainfall.

Either way, the chance for precipitation area wide does appear to be higher than it has in quite some time. I'm not yet confident in talking about specific rainfall totals as that could change in just a short 48 hours, but the potential is there for beneficial rainfall for some through Friday night.

Pleasant midweek weather gives way to Friday rain chances

Noticeably Cooler:

Cooler, drier air filtered in as yesterday progressed, allowing temperatures to start 10 to 15 degrees lower than they did Tuesday morning. The drop in humidity is also making for a much more comfortable and refreshing start to the day. 

  

Warm, but Dry Wednesday:

High pressure settling in nearby will provide plenty of sunshine throughout the day. While afternoon highs will end up similar to Tuesday, lower humidity levels will make a noticeable difference. Dew points are expected to remain in the upper 50s and low 60s, resulting in a comfortably warm afternoon with much less mugginess across the Stateline.  

Friday's Rain Chances:

Sunshine continues for Thursday, though high pressure will gradually give way to our next weather maker by Friday. While this system appears fairly weak, increasing cloud cover is expected Thursday night into Friday morning. 

Scattered rain showers will then develop and push in by mid to late morning Friday and continue at times through the afternoon. Again, if you are heading to day 3 of the Ogle County Fair or Day 1 of Festa, plan accordingly. It may be wise to have an umbrella with you.    

Why was there condensation on my window Monday morning?

 

Did you wake up Monday morning (yesterday) and wonder why your windows were wet? All the windows in our house had quite a bit of condensation on them. It's a pretty simple reason and really highlights the dew point temperature.

It doesn't happen all that often but tends to occur more on very warm and humid summer nights (like Sunday night/Monday morning). We cool the air on the inside of our house with our AC. That, in turn, cools the window. When the warm and humid air that is outside hits the cooled window the air begins to cool, reaching the dew point temperature. Since our dew points were pretty high that night the air didn't have far to cool. When that cooling takes place, condensation occurs. Think of it just like the dew that occurs on the grass in the morning. Or the condensation that forms on your car window when it's hot and humid outside and you have the air running.

And as long as the moisture is on the exterior part of the window - your window is doing its job. If it is in the middle, well then, you may need to replace some windows.