Weather experts say Chicago’s summer — which ended yesterday — was not ‘overly hot, cold, dry or wet.’

Labor Day traditionally signals the end of summer in Chicago, but weather experts said goodbye to the season on Wednesday.

That’s right, summer is over — according to meteorologists, who prefer to track weather in four, three-month increments instead of astronomical seasons, which are defined by equinoxes and solstices.

WGN-Ch. 9 chief meteorologist Tom Skilling is frequently asked why forecasters favor meteorological seasons.

“I prefer meteorological winter — and the other three seasons: spring (March to May), summer (June to August) and fall (September to November) — because they are unvarying in their beginning and ending dates. This is essential in making comparisons between seasons (temperatures, for example) from one year to another. The data are always from identical periods of time,” Skilling said.

We take a look back with local weather experts at the past three months and chose key dates to highlight the season′s significant events.

Overall, the season wasn’t a memorable one — when compared with recent years. The summer of 2020 included a significant derecho event and the summer of 2021 was marked by severe drought for the first time in a decade, said Illinois state climatologist Trent Ford.

“Looking back at this meteorological summer as a whole, there wasn’t anything that stood out to us in particular as this summer in its entirety wasn’t overly hot, cold, dry, or wet, nor did we see a distinguishably abnormal amount of any particular weather phenomena,” said Rafal Ogorek, a meteorologist at the National Weather Service Chicago. “However, there were still a few notable weather events that occurred this summer that we feel are worth looking back at.”

Warmest high temperature: 99 degrees

The first day of astronomical summer brought the heat. And though the century mark was not reached at O’Hare International Airport, the city’s official recording site, the metro area experienced some of its highest temperatures in a decade in June.

“This summer as a whole certainly wasn’t quite as warm as the past two summers, which finished among the top ten warmest summers on record in Chicago (the summer of 2020 remains as the warmest summer on record with an average temperature of 76.7 degrees, while the summer of 2021 is the 8th warmest on record with an average temperature of 75.3 degrees),” Ogorek wrote in an email to the Tribune. “But there were still a few periods of notable warmth, mainly during the month of June.”

He says there was a brief spell of hot and humid weather when heat indices in the Chicago area peaked in the 105-115 degree range, while O’Hare airport recorded high temperatures of 98 degrees on the 14th and 96 degrees on the 15th, the latter of which set a new daily record for June 15th.

About a week later, a renewed bout of hot and humid weather was briefly experienced with both O’Hare and Midway airports recording their warmest temperatures of the year of 99 and 101 degrees, respectively, on the 21st.

“Typically, we only see multiple days of 100+ degree temperatures when we’re in a drought, because that’s when evaporation and humidity are limited, which allow daytime temperatures to soar into the upper 90s and 100+,” Ford said. “However, since the start of July temperatures have, for the most part, been near normal.”

Coldest low temperature: 52 degrees

Though the cool snap did not set any records, it did provide some relief from mid- to late-June’s surge in above-normal temperatures.

Highest daily rain accumulation: 1.77 inches

Volatile conditions during the late evening hours of July 22 into the early morning hours of July 23 brought heavy rain, flooding and quarter- to golf-ball-sized hail in several locations around the Chicago metro area. Three early morning EF-0 tornadoes were also recorded in Will County.

[ Vintage Chicago Tribune: Tornadoes!!! ]

“While the overall amount of severe weather that we had this summer was more or less average relative to what was seen in recent years, there were a few notable events that packed a punch,” Ogorek told the Tribune.

• June 13: A supercell thunderstorm produced two EF-0 tornadoes in the northwest suburbs (one in Hoffman Estates and the other in Schaumburg and Roselle). Widespread strong straight-line winds downed numerous trees and power lines across parts of Cook and DuPage counties. An 84-mph wind gust was measured at O’Hare airport as this storm moved through and estimated 90-95 mph wind gusts caused notable structural damage in the near west suburbs of Chicago.
• July 4-5: Multiple rounds of storms produced damaging winds and minor flooding in northern Illinois.
• Aug. 3: Severe, scattered thunderstorms impacted the Chicago area with localized microburst winds of 60-70 mph.
• Aug. 7-8: Two rounds of heavy rain over 30 hours produced more than 5 inches of rain in northern Illinois and caused flash flooding. Rockford saw the highest precipitation total — more than 6 inches.

Fortunately, the damage seen with this summer’s severe weather events wasn’t quite as severe or extensive as the damage caused by severe weather that was seen in recent summers, Ogorek said.

From June through August, 9.21 inches of rain was recorded at O’Hare airport — that’s roughly three inches below normal. When looking at the calendar year, however, slightly more than 25 inches of rain have fallen so far — just one inch short of normal.

Afternoon Briefing

Daily

Chicago Tribune editors’ top story picks, delivered to your inbox each afternoon.

“Even though parts of the Chicagoland area are drier than normal this year, it’s nothing like what we saw last year or even in 2020,” Ford wrote in an email to the Tribune. “For the most part, northern Illinois has recovered from its drought of 2021. We still see some signs of the drought, namely in below normal groundwater levels that are monitored in McHenry County. Groundwater is the slowest recovering part of the hydrologic cycle, so it’s possible we don’t see groundwater levels in McHenry County return to normal until next year or after, even with normal rainfall.”

La Niña is sticking around: The climate pattern that has a cooling effect on ocean surface temperatures is expected to remain in effect through the end of the year, according to the World Meteorological Organization. This is the third consecutive year — or a rare “triple dip” — of the weather phenomenon.

“It’s unusual for a La Niña to hang on through summer, and even more unusual to go into a third consecutive La Niña —which we would if it hung on into fall,” Ford said.

Locally, the National Weather Service’s Climate Prediction Center is predicting temperatures leaning above normal and precipitation leaning below normal from September through November.

First freeze: The earliest first freeze on record occurred Sept. 22, 1995, at O’Hare. The latest was Nov. 24, 1931.

“The first freeze, which is when the temperature drops at or below 32 degrees, typically occurs between Oct. 11 and Oct. 12 across the Chicago suburbs and Oct. 21 to Oct. 30 in the city and along the lakeshore,” National Weather Service meteorologist Brett Borchardt told the Tribune in 2021.

[ When Chicago usually experiences its first fall freeze ]

Capture Chicagohenge: The autumnal equinox takes place at 8:04 p.m. Sept. 22. It’s the perfect time to experience — and photograph — Chicagohenge.