Labor Day’s 94 degrees missed the record by 1 degree. Heat, humidity, gusty SSW winds Tuesday—possible late day shower?

Better chance for gusty cold frontal thunderstorms
late Tuesday night

ONLY 7% OF CHICAGO’S LABOR DAYS SINCE THE HOLIDAY WAS DECLARED IN 1894 HAVE PRODUCED HIGHS TEMPS IN THE 90s

The hottest Chicago Labor Day was the 97 degrees reading recorded 69 years ago in 1954. 2023’s Labor-Day temp was 94 degrees and is the hottest Labor Day in the half century since 1973, one of the 8 hottest Labor Days of the past 129 years.

• Midwest temps have taken off in recent days. We’ve got a late season heat wave underway, and NOW HERE COMES THE HUMIDITY! Another hot humid day is ahead Tuesday and a humid day again Wednesday.
• Chicago recorded an official high of 94 degrees Sunday—3 degrees from the 1953, just a handful of degrees from the 1983 record of 95.

AREAS WEST AND NORTH OF CHICAGO REALLY SIZZLED

• High temps hit 100 degrees Sunday at Eau Claire and Cedar Rapids, Iowa, 99 degrees at LaCrosse, WI, 98 at Mason City, Iowa and 97 at the Twin Cities and Duluth, MN. Huron, South Dakota recorded a high of 103 degrees and Aberdeen, South Dakota topped out Sunday at 101 degrees.

WEATHER STATS FOR LABOR DAY, SEPTEMBER 4, 2023

Mississippi river levels are low again this year though not quite as low as last year

• STILL again this year, the low levels on the Mississippi are impacting barge traffic which has freight costs there soaring just as the 2023 harvest season approaches.
• As a Yahoo Finance reprint of this BLOOMBERG ARTICLE flagged in a post by hurricane expert and co-founder of Weather Underground, Dr. Jeff Masters (https://twitter.com/DrJeffMasters), the dry weather across a wide swath of the nation’s Corn Belt is impacting the water levels on the Mississippi River AGAIN THIS YEAR. This in turn, is impacting barge traffic which is critical in transporting a huge volume of crops harvested across our region to the markets of the world.
• The article points out barge rates soared 49% in the week ending August 29th and are up “….42% from last year at $23.34 a ton. That’s up 85% from the past three-year average, according to Department of Agriculture data…”

IT’S CERTAINLY BONE DRY HERE IN CHICAGO–IT HASN’T RAINED HERE IN THE PAST 18 DAYS

It should come as no surprise to Chicagoans that it’s dry. While it’s great to have Labor Day dry, the BIG PICTURE is that it hasn’t rained officially in Chicago for 18 consecutive days (nearly 3 weeks) as of today (Labor Day–Sept 4, 2023), and 5 of the past 6 months have been drier than normal. In fact, Chicago rainfall since May 1 has come in more than a half foot (6.62”) BELOW NORMAL.

CHECK OUT THESE CHICAGO O’HARE MONTHLY RAINFALL TALLIES

• April 2.02” (1.73” below normal)
• May 0.71” (3.78” below normal)
• June 2.36” (1.74” below normal)
• July 7.61” (3.90” ABOVE normal, the only wet month of the past
• 5 months)
• August 1.33” (2.92” below normal)
• Sept to date: 0” (0.49” below normal)

LAST THURSDAY’S “DROUGHT MONITOR” has much of the Greater Chicago area “MODERATELY DRY” and the area from McHenry, northern Kane and northern DeKalb counties west and northwestward in a state of “MODERATE DROUGHT.”

• Though surging humidities in coming days will likely give rise to some scattered t-storms, it’s going to be interesting to see the updated assessment of DROUGHT in next week’s DROUGHT MONITOR.

HOW HAVE METEOROLOGICAL SUMMER SEASON TEMPS CHANGED over past 75 years since 1949 in era of climate change?

• My friend and colleague Alaska-based National Weather Service climatologist Dr. Brian Brettschneider () answers that question with another in his always fascinating analyses–this one of the temp June, July and August average temp changes over the 75-year period since 1949. It underscores the fact we, in the Midwest, haven’t seen the dramatic warming other regions of the country have–in particular broad swaths of the Western U.S.–and to a lesser extent the Eastern U.S.
• Why might that be? I suspect a key reasons are increased cloud cover, likely a by product of the warming atmosphere’s increased ability to hold water vapor in these months fostered by widespread evapotranspiration (i.e. transport of moisture from soils and plants) which occurs over the region’s agricultural fields.
• These months are warmest of the year, therefore with an atmosphere with an increased moisture content and air more inclined toward buoyancy (i.e. the tendency of air to rise) because the season’s inherent warmth, it wouldn’t be surprising to see clouds increase.
• One other point to be made–ongoing warming across the Chicago has been most pronounced at night based on in house analyses we’ve done and in the colder months. Our winter temps are dramatically higher than back in the 1970s–a decade which produced Chicago’s coldest and snowiest winters overall–though the 1980s were home to our coldest individual temps–remember the 26 and 27-below readings recorded in 1982 and 1985?
• Dr. Brettschneider’s analysis illustrates how the temp change varies over country–it isn’t uniform–BUT IT IS OCCURRING and over a vast region of the country. And we know, from recent months, how the extreme heat has been making news in so many areas around us.
• When averaged across the country as a whole, Brettschneider points out that the average increase in temps over that period across the Lower 48 works out to around 1.5-deg. Doesn’t sound like much–but that’s a BIG DEAL with big consequences. This heat contributes to the warming oceans which fuel the faster intensifying and wetter hurricanes which have been a part of the scene with devastating impacts.
• IN YET ANOTHER POST, Brettschneider notes central North America was the outlier globally with its more restrained summer temps. Global June through August temps since 1940 have reached their highest level on record. He plots the global temp trend over that period and the trend is very clear. Dr. Brian Brettschneider’s work and posts can be followed here: