What a difference a day makes!  The official temp is likely to end up having peaked at 73-deg today—the equivalent of the normal high temps three weeks from now—on Sept 22-23—and a reading 14-deg off Tuesday’s 87-deg high. SO THERE WAS INDEED THE FEEL OF AUTUMN IN THE AIR TODAY.

Only a day remains in August and in the three month June, July and July meteorological summer season.  Midnight Thursday, with the arrival of September, 2023, marks the arrival of the three month METEOROLOGICAL AUTUMN SEASON, which runs through Sept, Oct and November.

September has historically been Chicago’s third fastest cooling month of the year losing an averaging of 10-degrees. Fastest cooling of the months is November which typically sees “normal” temps dip 13-degrees; 2nd fastest cooling is October which loses 12-degrees.  

Hours of daylight here have shrunk by 121 minutes since our longest day back on June 21—and we’ll see another 85 minutes of daylight disappear by the close of September. It’s a slow process but is slowly accelerating. 

Monday’s peak gusts of 25 to 30 mph, strongest along Lake Michigan, generated waves and rip currents on Lake Michigan which produced an unfriendly and hazardous environment for swimmers on area beaches. A BEACH HAZARDS STATEMENT remains in effect through late tonight—though diminishing overnight winds will allow waves on the lake to ease.  They’ve been running 3 to 8 ft. as measured at buoys on the south end of Lake Michigan.

Mid afternoon Monday temps ranged from 63-deg at Waukegan Harbor, 64-deg at Burns Harbor in Indiana and 65-deg at Calumet Harbor—to 75 inland at Lake Zurich and 73 at Naperville and Elwood.

A COOL NIGHT’S AHEAD—with the coolest low temps dipping into the mid to upper 40s in the chilliest spots well west and south of  the warmth of Chicago and Lake Michigan—while dropping into the mid 50s in the cities and holding close to 60 on the Lake Michigan shoreline.

BUT THE COOL WEATHER IS NOT LONG FOR THE AREA.  A temp rebound is on the way—AND HOT WEATHER IS TO BUILD INTO THE CHICAGO AREA for the Labor Day holiday weekend.  Temps will rebound to the upper 70s Thursday, the upper 80s Friday and into the 90s Saturday, Sunday, Monday, Tuesday and Wednesday next week—with NO RAIN expected until scat t-storms show up next Wednesday.

That means we’re in for an UNSEASONABLY WARM LABOR DAY WEEKEND and open to the new month of September which gets underway at midnight Thursday night. 

Temps over the coming holiday weekend are to average 8 to 14-deg ABOVE NORMAL—quite a departure from what’s usual this time of year!  And while a high temps of 94 is predicted Saturday; 97 Sunday and 98-Monday—low Saturday and Sunday humidities mean the heat won’t be as uncomfortable as it will become Monday, Tuesday and Wednesday next week when dew points surge into the 60s to near 70 and relatively humidities surge. Peak heat indices look like this right now:









TONIGHT: Clouds diminish—becoming clear and cooler with diminishing winds.  Low 54 in the city—but some mid to upper 40s coolest inland locations. (Reading on the lakeshore will drop to near 60).

THURSDAY—the final day of AUGUST 2023: Sunny and comfortable—afternoon temps close to seasonal norms and warmer than today.  High 79—but low 70s beaches.

THURSDAY NIGHT: Clear, cool. Low 64 in the city but mid to upper 50s inland.

FRIDAY: Sunny, warming continues.  High 88—but closer to 80 on area beaches.

SATURDAY and SUNDAY: Generous sunshine with afternoon temps growing hot—but with humidities remaining quite modest. Southwest winds are likely to overcome any lake cooling pushing warmth up to and out over the Lake Michigan shoreline. High Saturday 94 (peak heat index 92).  Sunday’s high 97 (Peak heat index 96).

MONDAY AND TUESDAY: Sunshine with some cottony fair weather cumulus clouds, breezy and hot each day with higher humidities. High Monday 98 and 94-deg Tuesday—with each afternoon’s peak heat index approaching 100-degrees.

WEDNESDAY: Partly sunny, breezy, hot and humid. Chance for scattered t-storms. High 91—Peak heat indices 95 to 100.