While a dangerous heat wave is expected to move into the Chicago area this week, experts said the summer has been relatively mild and only the city’s 40th hottest on record.
The temperature in the city is expected to reach almost 100 degrees on Wednesday and Thursday, and the heat index — a measure of what the temperature feels like when factoring in humidity — could reach up to 115 degrees in the Chicago area, according to the National Weather Service.
However, temperatures so far this summer have averaged about 84 degrees, which according to the weather service is on par with last year. And the short bouts of extreme heat this summer have been met by prolonged stretches of milder temperatures, said Dr. Trent Ford, state climatologist at the University of Illinois.
Chicago has had 13 days above 90 degrees this summer, Ford said. Last year, climatologists recorded 14 such days and 2020 saw 24 days where temperatures surpassed 90.
“We actually haven’t seen a ton of extreme heat this year,” Ford said.
Data collected over the last 30 years show Illinois hasn’t warmed as rapidly as other parts of the country, Ford said. And the short bursts of heat in Illinois this summer have not lasted nearly as long as the sweltering heat waves that have lingered in a large swath of the central U.S.
The heat wave hitting Illinois later this week is expected to last for two to four days, but Ford warned that short heat waves can be just as dangerous as longer ones, particularly when the intense heat is coupled with high humidity.
Meteorologists are advising residents to stay hydrated and seek shelter in cooler areas during the hottest days of the week. Those who have to spend time outdoors should know the symptoms of heat exhaustion, including dizziness, thirst, nausea and weakness. If not treated, heat exhaustion can lead to a heat stroke.
Those especially vulnerable to heat, like the unhoused or people with respiratory issues, can seek respite at one of the six cooling centers in Chicago, which are open on weekdays from 9 a.m. to 5 p.m., according to the city’s Office of Emergency Management and Communication. Chicago Public Libraries can also offer relief during operating hours. Chicago Public Schools CEO Pedro Martinez said all classrooms have air conditioning and schools can use gyms instead of sending kids outside for recess.
Temperatures are expected to drop below 80 degrees Friday as cooler air moves into the area.
Anna Savchenko is a reporter for WBEZ. You can reach her at @annasavchenkoo.