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.

Illinois on the brink of 200 tornado reports after recent outbreaks

Active Father's Day:

It's hard to believe that just last Friday, we were discussing about how Illinois had already surged past 160 tornado reports this year - a number that, on its own, already signaled an incredibly active season. Fast forward just a few days, and the atmosphere has only added to that mind-boggling total. 

Tornado Reports: 

After yesterday's tornado outbreak in central and southern Illinois, the statewide count is even higher, now sitting just a handful of reports shy of 200. 

What's even more staggering is how Illinois stacks up against the traditional severe weather hotspots. If you combine the total number of tornado reports from states like Nebraska, Kansas, Oklahoma, and Texas - they only edge out Illinois by four reports.

Less Active For Now:

Thankfully, Illinois finally gets a chance to catch its breath over the next few days. After an intense stretch of severe weather, the threat or highest potential will shift out of the region, moving into the Mid-Atlantic, as well as back west along the Rockies.  

Seasonably cool this week, summer-like heat returns next week

 Steady showers will clear out Sunday night, leaving us drier into Monday morning. While an isolated sprinkle cannot be completely ruled out Monday or Tuesday, most will remain dry as high temperatures reach the mid/upper 70s. Very similar temperatures are forecast through this entire week, with afternoon highs ranging between 76-77 every day through Saturday. Scattered thunderstorms will be possible Wednesday, but much of the remainder of the week looks drier.

However, the cool and comfortable pattern we have been in will not last much longer. There is an increasingly strong signal to see the summer-like pattern return beginning late next weekend. The long-term outlooks from the Climate Prediction Center support this, giving the Stateline a 50-60% chance to see above average temperatures between June 29th-July 5th. That would indicate more 80s and possible 90s on the way, more like what we come to expect in July. The warm-up also looks to arrive with much more humidity and storm chances as well. So, enjoy the 70s while they last!

Wet and cool Father's Day with steady rain showers

 Unfortunately, the forecast for Sunday is not nearly as pleasant as Saturday was with steady rain arriving by early afternoon. Rain will begin as early as 9-10AM for some of our Southwestern Counties and continue to spread Northeast through early afternoon. Southeast Wisconsin may not see rain start until after 12PM.

Steadier rain will be likely for everyone by early afternoon, with hourly rainfall rates near 0.25"/hr at times. A few rumbles of thunder will be possible as well, particularly in Southern portions of the area. While the heaviest rain will exit after 6PM, pockets of light to steady rain will persist into the night.

Temperatures will reach into the low 70s before/as rain starts but drop through the afternoon into the mid-60s as rain picks up in intensity. Winds will also pick up through the afternoon, gusting near 25-30 mph at times from the East.

Rainfall will add up much quicker for some compared to others. South of I-88 will see the highest rainfall totals, with some picking up between 1.0-1.5" or more. Between about I-88 and the IL/WI state line, you can expect between 0.5-1.0" of rain. Far NW Illinois and Southern Wisconsin may only see 0.25-0.5" of rain.

Illinois surpasses 160 tornadoes in 2026

It's been an incredibly active tornado season across the Illinois this year, with more than 160 preliminary tornado reports as of June 18th.

And given recent severe weather events, that number is likely still climbing. That total is 37 higher than all of last year and puts Illinois well ahead of the rest of the country, more than doubling Mississippi, which ranks second with 83 tornadoes. 

From early-season setups to multiple rounds of severe weather, the atmosphere has consistently favored storm development, fueling a prolonged stretch of frequent tornadic activity in recent years. And with the summer months still ahead, Illinois's tornado count will likely climb as we transition into M.C.S (mesoscale convective system) and Derecho season.