The streak of very warm nights ended Thursday as temperatures in the city dipped below 70 degrees for the first time since last Saturday.
Chicagoans sought relief during the daytime this week by heading to the beaches or public buildings with air conditioning, but warm nighttime temperatures created a particularly dangerous environment for the elderly.
At the beginning of the week, forecasters said it was possible the city would beat a more than 90-year-old record of seven days with evening lows in the 70s, but that didn’t happen. The overnight low at O’Hare Airport on Thursday night was 64, said Illinois State Climatologist Trent Ford.
However, the average five-day temperature at Midway Airport was just shy of 75 degrees this week, which is the hottest on record since June 1931, Ford said.
Temperature readings at O’Hare Airport were a little cooler during the past five nights at 72.6 degrees but that was the hottest stretch since 1958, according to Ford.
“The overnight heat this week has been remarkable for this time of the year,” Ford said.
City public health officials have been studying heat trends and say they know more about geographic differences and other patterns, though it’s unclear what plans are in place to better protect Chicagoans from extreme heat.
For now, city officials recommend seniors and other residents vulnerable to heat-related illness to seek refuge at city cooling centers or libraries. They’ve provided almost no options for seeking cool spaces at night, however.
On Wednesday, the city left open only one cooling center and closed all 81 public libraries for the Juneteenth holiday.
The heat index, a measure of heat and humidity, was very high all week, peaking at 101 at Midway on Monday afternoon and 98 at O’Hare on Sunday afternoon, Ford said.
The city marked four days of highs in the 90s, which is uncommon but not unheard of. There was a four-day stretch of similar high temperatures in June of last year, Ford said.
The forecast for the next few days shows a mix of temperatures with a better chance of rain. Temperatures are not expected to climb into the high 90s.
