Northern Illinois under extreme heat warning until Friday

90-Degree Day Stats:

Yesterday marked just the second time this year that temperatures at the Rockford Airport climbed to 90 degrees or higher. For perspective, we typically see about four 90-degree days between May and June combined, meaning we're running behind schedule when it comes to the true summer heat. That trend is about to change, however, as a strengthening ridge of high pressure helps keep this extremely hot air mass in place for the start of July. 

Extreme Heat Warning:

The National Weather Service has now upgraded the remaining counties across the Stateline to an Extreme Heat Warning, meaning all of our counties are now under the warning through 12AM Friday. The length of this warning speaks volumes about just how long this true summer heat will be, as several consecutive days of intense heat continue to place added stress on anyone spending time outdoors.    

Dangerous heat index values around 105 degrees are expected this afternoon, Wednesday afternoon, and then Thursday afternoon, with little relief occurring during the overnight hours. Afternoon highs will peak in the low 90s today, then in the mid 90s for the middle of the work week. Though this is wildly hot for this time of year, our forecast highs won't be close to our record highs which for today and tomorrow, ended up over the triple-digit mark.  

Heat Safety Tips:

With the extended stretch of heat and humidity on the way, it will be very important to practice heat safety this weekend. Some tips include drinking plenty of water, taking many breaks in the shade and A/C, and limiting exposure to the sun. Also, look before you lock the car or house. Never leave children OR pets unattended outside or in a vehicle. 

Extreme heat returns to northern Illinois this week

Extreme heat is expected across the Stateline over the course of the next week. Temperatures in the low-to-mid 90s will combine with high dewpoint temperatures to create potentially dangerous conditions. An EXTREME HEAT WARNING is in effect for all of our Wisconsin counties from noon today through 7p Tuesday. We also have the same warning in effect for Jo Daviess, Carroll, Stephenson and Whiteside counties from noon today through 10p Wednesday. Finally, a HEAT ADVISORY is in effect for the rest of the Stateline from noon today through 10p Wednesday. 

These heat headlines are issued when heat index temperatures are expected to be or exceed 105 degrees for a prolonged period of time. Dewpoints in excess of 70 degrees will combine with temperatures in the 90s to create what is expected to be our first dangerous heatwave of the summer 2026 season. As seen in the graphic below, 4 days of heat indices over 100 degrees are expected. This is thanks to a strong area of high pressure camping out to our south.  

Today, expect a high near 92 degrees, with heat indices approaching, if not exceeding 100 degrees. Partly cloudy skies will give way to enough sunshine to make the heat feel extreme at times. Additionally, a gusty southerly wind will allow us to warm quickly into the 90s this afternoon. 

So, let's talk heat safety. NEVER leave pets or children unattended in vehicles! Make sure to look before you lock. Check on neighbors, elderly and those without air conditioning. They are the most susceptible to heat related illnesses. Limit outdoors time during peak heating. Find shade and drink plenty of water.

Finally, know the difference between heat exhaustion and heat stroke. Heat stroke is a medical emergency. If you or someone you know suffers a heat stroke, dial 9-1-1 immediately!

Pleasant Friday across northern Illinois, oppressive next week

Cooler Start to Summer:

It's been an unusually cool start to the summer season across, with comfortable air consistently winning over typical early-season heat. In fact, since May 1st, days topping out in the 70s have nearly outnumbered those reaching the 80s and 90s combined. We will likely see once last cool and comfortable before summer wakes up and brings the heat and humidity back.    

Cool, Isolated Shower:

Today will stay on the cool side, with afternoon highs settling into the low to mid 70s. Clouds will be around for much of the day as a weak storm system or an M.C.V slides across the southern Illinois. While most of the Stateline will stay dry, precipitation could track north enough for us to see a shower or two. Conditions remain dry overnight, with temperatures falling into the upper 50s.  

Summer Heat Returns:

After a brief warm-up into the 80s over the weekend, a surge of warm air advection combined with strengthening ridging aloft will send the 90s back right into the Stateline. In fact, high temperatures on Tuesday and Wednesday run 20 degrees warmer than what have in the forecast today. Of course, next week's southerly to southwesterly wind will send dew point temperatures into the low 70s, making it feel more oppressive across the area. This will also be the type of stretch where there's little relief at night, with overnight lows only falling into the low to mid 70s, offering minimal cooling before the next hot and humid day. 

Enjoy the 70s while you can - 90s returns next week

Remaining Comfortable:

It's been an impressively comfortable second half of June across northern Illinois, with temperatures running below typical early-summer levels. We've seen a steady run of cool afternoons and low humidity, making it feel more like late spring at times than early summer. In fact, yesterday marked the 12th day this month where afternoon highs didn't even make it to the 80-degree mark.  

For those, like me, who love this kind of comfortable weather, the good news is it sticks around for a few more days before true summer kicks in. Today will feature more of the same, with afternoon highs in the upper 70s under a partly cloudy sky. Rain chances stay low as the recent storm system pulls away, and with a light breeze out of the west and northwest, humidity levels will remain in check. Conditions stay cool and comfortable overnight into Friday, with lows dropping into the upper 50s. 

Friday keeps the quiet stretch going with comfortable and dry conditions, as afternoon highs once again will settle into the upper 70s. Rain chances will be low for much of the day, though an isolated afternoon shower cannot be ruled out as a weak storm system slides across the southern half of the state. 

 

Summer Heat Returns:

A strengthening ridge of high pressure will the take over, helping to crank up the summer heat late this weekend into next week. So far, Rockford hasn't seen a single 90-degree day this June, but that's likely to change as we get to the end of the month. 

Afternoon Highs are expected to climb into the 90s starting Tuesday, marking a noticeable shift in the pattern. And of course, with that heat will come increasing humidity, pushing heat index values into the triple-digits on multiple days next week, especially Wednesday. For those reasons, enjoy these cooler, comfortable days - and the chance to keep the A/C off while you can. 

Summer heat and humidity set to return next week

 

We've gotten used to the cool nights and warm afternoons the last week and a half as temperatures have been running a bit below average. But that'll all be changing by the weekend/next week as the summer heat is set to make a quick return.

In the short-term, temperatures will remain slightly below average through the rest of the week with highs in the upper 70s. The average high this time of year should be in the low 80s. Following the passage of

low pressure and a cold front Wednesday, high pressure will build back in across Canada. This will help keep us under an easterly breeze through the start of the weekend. But as low pressure develops to the west a strong ridge of high pressure will develop over the east and southeast, pushing the jet stream northward. This will cause temperatures to climb back into the 80s as early as Saturday, then upper 80s on Sunday.

As the ridge grows even stronger into next week it's likely we'll see temperatures reach the low 90s, possibly for several days in a row. Dew points will also be on the climb which means the heat index could reach the upper 90s, close to 100 degrees, on a few of those days. We do have to watch just how close to the outer edge we sit as that'll be the path for showers and thunderstorms. Should any storms move through, either at night or during the day, that could impact the extent of the warmth next week. 

 

Pleasant today, watching Wednesday for isolated severe storms

Pleasant Tuesday:

High pressure remains in control today, keeping conditions across northern Illinois quiet, comfortable, and largely storm-free. 

Skies will remain partly cloudy through the afternoon, helping temperatures climb into the upper 70s, right near that 80-degree mark. With point settling in the upper 50s, it'll feel similar to Monday, refreshingly less humid making for a pleasant early-summer day. Also, perfect weather for Food Truck Tuesday! Now, if we do see temperatures stay shy of the 80-degree mark, today would mark the 11th day this June with highs in the 70s, highlighting just how below-average this month has been. 

Isolated Severe:

Cloud cover will begin to increase overnight into the early stages of Wednesday as an occluded low and a warm front draw closer to the Stateline. As we move into the warm sector by Wednesday afternoon, there may be enough instability in place to support an isolated threat for strong to severe storms during the late afternoon and evening hours.  

The primary concerns will be pockets of damaging wind and hail, but with added spin in the atmosphere from the nearby surface low and lingering boundaries, an isolated tornado cannot be ruled out. For that, the Storm Prediction Center has placed areas along and north of I-88 under a Marginal Risk. Afternoon highs tomorrow will be similar to this afternoon, landing in the upper 70s. Same for Thursday.  

Unseasonably chilly start to Summer

 

If you thought the start to the summer solstice Sunday was a bit chilly, you'd be correct. Rockford officially reached a high of 68 degrees, but once the rain started temperatures cooled through the afternoon. While it was a steady, soaking rainfall it did not feel anything like summer Sunday afternoon.

According to the National Weather Service Chicago the high of 68 degrees was the coolest first day of summer since June 21, 2018, when Rockford reached a high of only 65 degrees (records dating back to 1905)! That date also tied with June 22nd, 1906, as the coolest observed first day of summer.

Dating back to 1905, there have only been 8 summer solstice days with a high temperature in the 60s in Rockford, including yesterday afternoon. Thankfully, our temperatures are looking up (and that started with Monday). Highs the rest of the week will be in the 70s, although still just a bit below the average high of the low 80s. Soon, though, the summer heat and humidity will return. I'll have more on that in a later post.