It’s been another hazy, warm summer day with warm BUT SEASONABLE TEMPS in Chicago. EPA reports the air quality here has been moderate—not unusual this time of year but with the added presence of some Canadian wildfire smoke aloft. The agency cautions moderate air quality which could affect folks with respiratory challenges on Thursday. 

Low and mid 60-degree dew points indicate atmospheric moisture levels in the “MODERATE” range—enough to notice, especially leaving an air conditioned room—but not enough to cause major distress outdoors unless exercising real exertion. 

A gentle easterly lake breeze has reduced temps modestly along Lake Michigan. We’re beyond the point, given the warming which has gone on with water temps, that MAJOR COOLING ISN’T OCCURRING. The Chicago shoreline water temp has reached a seasonal high of 74-deg on city beaches. At mid afternoon, Greater Chicago area air temps ranged from 77 on the lakeshore at Wilmette and Lake Forest and 75 at Kenosha—but in the low 80s at Calumet Harbor, Gary and Burns Harbor in Indiana. The warmest inland temps Wednesday have reached 86 at Tinley Park and Lake in the Hills with 85-deg readings at Elburn and Warrenville.

Localized downpours are passing well west of the Chicago area in sections of southern Iowa where the deep moisture resides. A southeastward moving t-storm cluster, which is bypassing the Greater Chicago area has unleashed 5.50″ on Van Wert—4.38″ at Hancock–3.25″ at Kellerton and 2.04″ rains at Humestown—in south central Iowa and western Iowa. The storm cluster responsible for the mega rains is the product of the continuing RING OF FIRE pattern to our west, which occurs when t-storm clusters rotate around domes of hot air—like the one which has again today pushed temps to triple digits in the Plains from Kansas south into Texas. 

Rain prospects are minimal in Chicago through Friday night. There’s just the chance of an isolated southbound shower in spots late Thursday night.  This comes on the heels of a July which produced monthly rain totals which exceeded one foot (12.25″) at Oak Lawn and 12.12″ at Rogers Park on Chicago’s North Side.  O’Hare ended up with an eye catching 7.61″—195% the 3.90″ considered normal for the month. That was enough to lend July 2023 a ranking of 7th wettest of all the Julys since 1871.  Midway broke the record for the month in the 95 years dating back to 1928 that observations have been taken and archived there.

Thursday temps return to the 80s with humidities coming up Thursday as indicated by dew points likely to reach closer to 70-deg—a steamy level of moisture—later in the day.  A lake breeze will again produce moderately lower high temps on the shoreline.

A tightening pressure gradient may most easterly wind velocities Friday increasing the chop on Lake Michigan for mariners and swimmers alike.

BUT THE BIG WEATHER STORY MAY BE THE POTENTIAL FOR ACTIVE T-STORMS CLUSTERS SWEEPING IN SAT NIGHT INTO SUNDAY AND SUNDAY NIGHT amid steamy 70+-deg dew points.  With moisture levels like that, the potential for significant downpours parts of the day appear elevated. Model rainfall estimates vary as they always do this time of year. But they’re bracketed in the 0.60″ to 3.10″ range which means we’ll be keeping a close eye on that system—currently out in the Rockies—as it sweeps east into the Chicago area.

The potential for SEVERE WEATHER MAY BE WITH US AS WELL with a warm, very buoyant and energetic air mass in the area and a jet stream overhead.  

And it may not be the last significant rain threat. Another system is showing up on medium range models in the Wed night through Friday time frame next week.


TONIGHT: Partly cloudy, hazy and warm with moderate humidities and some shallow patches of ground fog in some surrounding areas.  Low 69.

THURSDAY: Partly sunny, hazy and warm. Higher humidities as the day proceeds and moderate air qualities and easterly lake breezes. High 90—but low 80s on area beaches.

THURSDAY NIGHT: Partly cloudy, hazy, warm and humid. Chance of a few spotty showers late. Low 72.

FRIDAY:  Mixed sun and summertime cumulus clouds, warm but easterly wind picking up a bit. High 86—but upper 70s to around 80 lakeshore.

SATURDAY: Partly cloudy, warm and moderately humid. Slight chance of an afternoon or evening t-storm—-but better prospects for some showers and t-storms at night. High 86—low 80s  beaches.

SUNDAY and SUNDAY NIGHT: More clouds, warm and noticeably muggier.. Clustesr of showers and gusty t-storms capable of downpours. The area will have to be monitored for potential severe weather. High 84.

MONDAY: Partly cloudy, warm, still humid. Several showers or t-storms possible. High 81.

TUESDAY: Partly sunny, warm, moderate humidity.  High 81.