Extreme heat lingers as storm chances eeturn this evening

Extreme Heat Continues:

There were a few minor adjustments made to the Extreme Heat Warning last night. The National Weather Service removed Jo-Daviess, Carroll, and Stephenson Counties from the warning as slightly lower temperatures and heat index values are expected in those areas. However, the rest of the Stateline remains under the Extreme Heat Warning until 12AM Thursday night.   

Hot Thursday Ahead:

As for today's forecast, a few isolated thunderstorms remain possible early this morning, but much of the day will feature partly cloudy skies. Despite the slight drop in humidity compared to the past few days, high temperatures remain the same, peaking in the low 90s for the 4th consecutive day. When combined with the lingering humidity, heat index values will approach the 100° mark and may briefly rise above it for an hour or two during peak heating hours. 

Storm Chances Return:

Along with keeping an eye on the heat, watch for severe potential this evening into tonight. Much of that potential will depend on whether the atmosphere can recover following a round of showers and storms that pass through Wisconsin early in the day. It also will depend on if the frontal boundary responsible for redevelopment remains intact or fizzles out as it slides closer to the Illinois/Wisconsin border. 

Highest severe threats will be strong winds, along with frequent lightning and heavy downpours. For that, the Storm Prediction Center has areas  under a level 2 of 5 Slight Risk for scattered severe storms. They also have a level 2 of 5 Slight Risk in place for the entire Stateline area tomorrow as a secondary boundary sinks south.  
 

Pattern breakdown leads to a gradual increase in thunderstorms heading into the 4th of July weekend

 For the third day in a row, afternoon temperatures have warmed into the upper 80s and low 90s, with the heat index climbing to 100 (or higher). Extreme Heat Warnings remain in place through tonight for Stephenson, Jo Daviess, Carroll counties and until Thursday night for Whiteside, Rock, Green, Walworth, Winnebago, Boone, Ogle, Lee, DeKalb, and McHenry counties.

Isolated thunderstorms developed over parts of northeast Iowa earlier Wednesday afternoon, shifting northeast into Wisconsin but had a hard time maintaining their strength and were quick to dissipate over Green County. With skies beginning to clear Wednesday evening the chance for any thunderstorms locally remains very isolated. It'll continue to be a hot and muggy evening/night.

Storms are likely to get going over the next few hours from parts of Wisconsin, back through Minnesota and Iowa. This is where the stalled cold front/stationary boundary resides. While most of those storms will remain to our north overnight, the slight shift in the upper-level ridge will set the stage for a little further southward development of any storms tonight. This could lead to an isolated storm or two moving into parts of southern Wisconsin and northern Illinois through sunrise Thursday. The main threat for any severe weather resides to our north, but a gusty storm or two may occur locally should any storms move towards the state line late tonight.

While there may be some impact with regards to temperatures Thursday morning, the expectation is for highs to climb back into the upper 80s and low 90s. As the stationary boundary stalls a little closer to the state line the chance for showers and thunderstorms will gradually increase through the weekend, but it doesn't look to be a complete washout.

Heading into Thursday evening we'll need to keep an eye on any storm that develops locally as there could be a risk for a severe storm or two. Southern Wisconsin and some of northern Illinois are under a 'slight' risk for severe storms Thursday evening. A 'marginal' risk for an isolated severe storm is in place for Friday. Should any storm reach severe limits it would be capable of producing strong winds and hail.

  

4th of July preview: Not as hot, scattered thunderstorms possible

 Historically, the 4th of July is one of the hottest holidays of the year. It is right in the middle of summer, when our average high is in the mid-80s. Recent Independence Day holidays have been more of the same, with an average high of 88 degrees since 2020. Six of the last eight years have featured 90-degree days for the 4th!

This year will be right in line with recent years. Highs will reach the upper 80s with some humidity and isolated to scattered thunderstorm chances. Right now, our forecast high is 87 degrees!

Scattered thunderstorms will be possible from time to time, so it will be a day to watch the radar very closely. Highest coverage of rain appears to be mainly early in the day, with lower coverage toward the evening, but that is subject to change based on any lingering boundaries from previous storm complexes Friday into early Saturday morning. Stay tuned to the forecast for future updates!

Another sizzling day across northern Illinois as heat indices near 100° again

Heat Alerts Continue:

There have been no changes when it comes to the heat alerts for the local area. All Stateline counties remain under an Extreme Heat Warning until 12AM Thursday night.  

 

  

Another 90-Degree Day:

Another hot summer day is on tap for northern Illinois, with afternoon highs climbing back into the low 90s under a mixture of sun and clouds. A warm wind out of the southwest will continue to pull in humid air, leaving dew points temperatures in the low 70s. That added moisture will make it feel even hotter, with heat index values hovering around the triple-digit mark this afternoon. 

Heat Safety:

Like you've done the past few days, be sure to take frequent breaks in the shade or A/C if you have to be outside for a prolonged period of time. Stay hydrated by drinking plenty of fluids not including alcoholic or carbonated/caffeinated beverages.  
 

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.