Another HOT ONE in Chicago! Temps are likely to top out at 93-deg making this the 20th day at O’Hare at or above 90-deg this year—18 at Midway.  HEAT INDICES have average in the mid 90s Tuesday given dew points which are high—ranging from the upper 60s to low 70s.

Also of note, this is the SUNNIEST OPENING 5 DAYS OF A SEPT in the 68 years since 1955, reports Frank Wachowski. Sept 2023 has opened with 95% of its possible sun. Sept 1-5, 1955 opening with 97% of its possible sun.  A preliminary estimate of sun today came in at 83% of that which is possible.  Clouds have moved in late  this afternoon and it wouldn’t be surprising to see the sunshine estimate revised down a bit before the sun sets Tuesday evening.

It hasn’t rained officially here in 19 days—though weather radars locally are aglow with some showers—so that may change

The drier than normal weather to date may be having an impact is stressing trees here leading to a color change earlier than might otherwise occur. To date—Sept is running a deficit approaching 0.50″—but since April 1, the area has received just 67% its possible rain. And rainfall in August was not even a third normal (31%).

BIG WEATHER CHANGES LOOM. A cold front passes late tonight and may generate 40% coverage scattered gusty t-storms in the 1am and 6am time range after this evening’s spotty showers move on.

Gusty winds will blow in Chicago Wednesday. Humidities and dew point are to remain elevated going into Wednesday morning even though rains will have moved on for a time. But those will begin to drop off Wed afternoon and evening. Still, daytime heating may generate enough instability to pop a few spotty showers later in the afternoon and early Wed evening—one or two of which which may produce lightning.  But areal coverage on those will be quite limited.

It’s tomorrow night and forward through the coming weekend and into next week which temps will cool. There’s to be the general feel of autumn in the air. Daytime highs will hold to the upper 60s to low 70s Thursday through Saturday—and the coming weekend is likely to average 12.5-deg cooler than last.  THAT’S QUITE A CHANGE! 

What’s more northeast winds are likely to travel down Lake Michigan into Chicago and this is likely to produce 60s on area beaches Friday into Sunday.

WHILE THERE MAY WELL BE CLOUDS Thursday into Friday amid some gusty north/northeast winds—no rain of consequence is anticipated.

And the potential for some showers in the cool air with a disturbance in the late Monday into Tuesday time frame, rainfall tallies at this distance don’t look especially large.

IN THE ATLANTIC—It looks like we could have a MAJOR HURRICANE in the making. It’s just a disturbance at the moment and NO WHERE near land.  But is could spin up to a CAT 4 or 5 hurricane with 140+ mph winds as it churns west/northwest by week’s end. Current track projections send it north of the Leeward and Virgin Islands—but NHC forecasters urge caution noting that track errors in model guidance at that range in time make it too early to dismiss impacts on those islands. 


TONIGHT: Several showers possible early. Then breaks in the clouds, warm and humid with scattered gusty t-storms possible over 40 to 50% of the area in roughly the 1am to 6 am time frame.  Low 73.

WEDNESDAY: Windy and initially humid. Mixed clouds and sun, not as hot—but still well above normal. A few scattered showers, possibly a t-storm may “bubble up” over 20 to 30% of the area later in the day or evening.  High 88 with humidities trending lower later in the day.

WEDNESDAY NIGHT AND THURSDAY: Mostly cloudy, breezy, cooler and less humid. Low Wednesday night 60—some mid 50s inland. High Thursday 71.

FRIDAY: A good deal of cloudiness—but some cloud breaks later in the day may allow mixed sun. Breezy and cooler. High 71—60s along Lake Michigan.

SATURDAY: Mostly sunny, seasonably cool. High 72—60s lakeshore.

SUNDAY: Partly sunny, seasonable temps. High 75—closer to 70 lakeshore.

MONDAY: Increasing cloudiness. High 74—60s at the lake.

TUESDAY: Showery, cool and breezy.  High 71.