Pockets of steady to heavy rain Friday evening into Saturday

 [10:40PM] Pockets of steady to heavy rain will continue through the overnight window and into Saturday morning. Heaviest rainfall rates may exceed 1" per hour at times. Another 0.5-1.5" possible for some, with minor flooding concerns in low-lying areas.

[9:30PM] Steady rain persists for most late this evening with embedded pockets of heavy rain. Rain continues through the night and into Saturday morning, with the bulk of the remaining rainfall coming after midnight. Already, many to the West of I-39 have seen near or more than 1" of rain, with another 1-2" possible by the time rain ends Saturday evening. Be on the lookout for standing water in low-lying areas Saturday morning!

[6:15PM] Pockets of steady to heavy rain are moving back into the Stateline, especially across Jo Daviess County. There, some instantaneous rainfall rates are near 2-3" per hour. The slow-moving nature of these showers will result in quick accumulations as cells move to the Northeast at around 20-25 mph.

Coverage of rain will continue to increase through the evening, with likely widespread steady rain by the time we reach 8-9PM. Embedded within will be the heavy rainfall rates, possibly near 2-3" per hour at times. If these cells track over the same areas over and over again, rain will accumulate rather quickly. Be on the lookout for isolated flooding in low-lying areas this evening and tonight!

A good soaking rain with pockets of heavy rain will likely continue through the nighttime window and into the early morning hours of Saturday. Rain will finally begin to wind down after 4AM.

While the heaviest rain will be ending, light to steady rain will then continue through Saturday morning. Scattered showers will then remain possible through the duration of Saturday afternoon before rain comes to an end by the evening.

It will remain cool and breezy throughout, with limited temperature range Saturday. The morning will start in the mid-60s, and temperatures will only rise into the low 70s with a stout Northeasterly breeze. Wind gusts could reach 20-30 mph at times.

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.

Hazy skies return thanks to upper-level smoke

 

Summer smoke makes a return to our Stateline skies Tuesday thanks to the northwest position of the jet stream and a passing cold front late Monday night/Tuesday morning. But unlike our last bout with wildfire smoke, most of this smoke will remain in the upper levels of the atmosphere. There will still be some impacts to our air quality over the next couple of days as we remain in the moderate category. For the current air quality and forecasts, you can click here.

The smoke is coming from fires over the Pacific Northwest as a ridge of high pressure sits across the southern Plains. This continues to bring high heat to the south but allows the smoke to move across some of the northwest, Plains, and across the Great Lakes. Thanks to an upper-level inversion in our atmosphere that smoke isn't able to easily mix down to the surface, although there may be some that tries late Wednesday and Thursday. This may be more of an issue to our west than for us locally.

As our winds remain positioned from the northwest in the jet stream, we will likely continue to see at least some smoke impact our skies throughout the week.

What you'll notice more of, however, will be the reddish sky during the sunrise and sunset. This has to do with the smoke particles in the atmosphere, scattering more of the blue/violent light wavelengths. Those wavelengths are shorter and tend to scatter easily, leaving behind the red and orange light wavelengths. And because the sun's light has a longer distance to travel through our atmosphere during sunrise and sunset, more of the blue/violet light gets scattered, leaving behind the red. Depending on the thickness of smoke this could leave us with a very vibrant sunrise/sunset, or more of muted one.

Intense heat takes a back seat as July comes to a close

Hottest Day of the Year:

Monday (as of right now) is written in the books as the hottest day of the year for northern Illinois and southern Wisconsin. Temperatures soared into the mid to upper 90s for most locations. Combined with the tropical humidity and dew point temperatures in the upper 70s, heat indices climbed to very dangerous levels between 110° and 120°.  

While yesterday's heat sure was extreme, it's not the hottest we've been in recent years. For example, the Rockford airport recorded its first 100-degree day in a decade when the temperature reach 100 degrees on June 14th, 2022. Prior to that, the city had not hit or seen the century mark since 2012. 

  

Cooler, Less Humid Tuesday:

The good news is that yesterday's intense heat appears to be the peak of this most recent stretch, as afternoon highs are set to take a "chill pill". Thanks to a cold front that swept through the region Monday evening, highs today will be much closer to where they should be for late July, topping out in the low 80s. While the day will begin on a muggy note, noticeably drier air will filter in behind the front. 

Rain Chances Increase Late:

This stretch of comfortable weather should make for a rather great start to the Ogle County Fair, which gets underway Wednesday, July 29th, with dry conditions expected through the first few days. As we head into the latter half of the week, however, rain chances will begin to creep back into the forecast. Days 3 and 4 of the fair, along with days 1 and 2 of Festa Italiana at Boylan High School, could see a few showers as a weak system tracks to our south and west.  

Limited thunderstorm chances Monday evening

 

Numerous severe thunderstorms moved around the Stateline late Monday morning and afternoon, prompted several severe thunderstorm and tornado warnings. The storms formed along the outer edges of the high heat, humidity, and instability and were very quick to intensify across Wisconsin and northeast Illinois. There were several reports of large hail, damaging winds, and tornadoes. This left the majority of the immediate viewing area high and dry, and just plain hot and humid! Peak heat index values reached upwards of 115 degrees during the afternoon, with a couple sites even coming close to 120!

While our focus has been on the heat and humidity this afternoon, there are a few showers that are starting to develop along a couple outflow boundaries this evening located across Rock County. A few showers have popped between Janesville and Beloit and are drifting to the south/southeast.

Should the showers continue to develop there is still enough heat and instability to allow for an isolated storm or two through 9pm. And with the amount of instability a severe storm or two cannot be ruled out. So, with that I think our highest chance for thunderstorms (still around 20-30 percent coverage) will be along and east of I-39 through late evening. Should any storm reach severe limits, strong wind gusts and very heavy rainfall can't be ruled out. I'll be keeping a close eye on radar over the next couple of hours.

  

Extreme heat, storm potential also on the table across northern Illinois

Extreme Heat Warning:

Along with the dense fog potential, we also have extreme heat and the threat for strong to severe storms on the table today. Storms will be possible during the morning hours, with a secondary round potentially developing during the late afternoon hours. 

In addition, Winnebago, Stephenson, Jo-Daviess, Carroll, Ogle, Lee, DeKalb, and Whiteside County are under an extreme heat warning until 9PM, where heat index values could climb well into the triple-digits. The rest of the Stateline, including Boone and McHenry counties in northern Illinois as well as much of southern Wisconsin, have been placed under a heat advisory.  

Hot & Humid Monday:

Temperatures are expected to soar into the 90s once again today, and when combined with dew points in the mid to upper 70s, it will feel even hotter outside. These tropical levels of humidity will push heat index values into the 105 to 115 degree range this afternoon, creating dangerous conditions for anyone spending long periods of time outdoors. 

If you do have outdoor plans today, be sure to drink plenty of water, even if you don't feel thirsty. Take frequent breaks in air-conditioned buildings or shaded area, wear lightweight clothing, and avoid strenuous activities during the hottest part of the afternoon.  

Severe Storm Update:

Today's severe weather threat will be fueled by the extremely warm, humid, and unstable air in place ahead of southeastward-diving area of low pressure and the associated cold front. 

With lots of moisture, instability, and lift in the atmosphere, the environment will be conducive for a few strong to severe storms. Though there isn't much going on across Wisconsin at the time of this article, we'll still going to keep a chance for a few isolated storms during the early morning hours. However, forecast models have shifted the main thunderstorm potential towards the midday and early-afternoon hours. The Storm Prediction Center has placed much of the Stateline under a level 3 of 5 Enhanced Risk, indicating the potential for numerous severe storms capable of producing damaging winds and an isolated tornado or two. Make sure to stay weather aware throughout the day and have multiple ways to receive severe weather alerts.   

Dense fog advisory for all of northern Illinois until 8AM

What's Ahead: 

It's a busy start to the work week across the Stateline, and it all begins with very dense fog. 

 

 

   

Dense Fog Advisory:

A Dense Fog Advisory is in place for the entire area until 8AM, with visibility dropping to a quarter mile or less at times. The thick fog will make for difficult travel conditions during the morning commute, so be sure to slow down, use low-beam headlights, and allow for extra travel time. Conditions will gradually improve after sunrise as the dense fog begins to lift and visibility improves.  

Strong thunderstorms possible Monday morning, humid afternoon

 Strong to severe storms still remain possible overnight into early Monday morning. With the lack of a trigger, the atmosphere has remained calm so far today. But a complex of storms may dive across the area around 5-9AM, bringing strong winds and heavy rain. There is still a low-end chance we see something develop before then, but the main wave looks to arrive early Monday morning.

Models have a very hard time pinpointing exact timing of these sorts of patterns, so do not take this Futurecast picture as gospel. Chances for storms will increase after 5AM, and a severe storm may be possible through the course of the day. Be sure to have multiple ways to receive warnings and a plan to carry out should a warning be issued.

The influence from that morning complex will determine what, if anything, we see for Monday afternoon. Remnant boundaries, including a lake-enhanced boundary, may induce extra spin to allow for an isolated tornado threat to develop, should any storms form Monday afternoon. Once the cold front clears toward late evening, we will be done with the severe threat.

Outside of the storm potential, it will be another very hot and humid day. Confidence on heat index pushing 105°+ area-wide is not as high Monday as it was Sunday, so the heat advisory was allowed to expire for most. For NW Illinois, it remains in effect through Monday evening. Those who do not see any storms will likely see a heat index well over 100°.

Some wildfire smoke will make a return Monday evening, especially aloft. If any gets trapped under the incoming high pressure Tuesday, we could see some minor air quality concerns. But for now, that smoke does not appear to be all that dense, with forecast air quality in the "moderate" category.