Extreme Heat Watch Issued for Chicago as Heat Index Nears 115 Degrees

CHICAGO — An extreme heat watch has been issued for northeastern Illinois, including Chicago, as oppressive humidity and soaring temperatures are set to push the heat index between 105 and 115 degrees through midweek.
According to NBC Chicago, Tuesday will begin with highs in the mid-to-upper 80s, but rapidly climbing dew points will make conditions feel hotter by evening — setting the stage for a heat surge on Wednesday and Thursday.
“Miserable” Humidity to Blanket the City
NBC 5 Meteorologist Alicia Roman warns that dew points will reach the mid-70s, creating what she described as “downright miserable” humidity. The National Weather Service (NWS) echoed the concern, stating that the oppressive combination of heat and moisture poses a serious risk of heat-related illness, especially for vulnerable populations.
“Dangerously hot conditions with heat index values of 105 to 115 degrees possible,” the NWS noted.
The extreme heat watch remains in effect until 10 p.m. Thursday, while neighboring northwest Indiana will be under a heat advisory.
‘Corn Sweat’ Worsening Rural Heat
Residents in rural and agricultural zones near cornfields are expected to face even higher localized humidity due to a phenomenon known as “corn sweat.” As corn plants release moisture in an effort to cool themselves, the added vapor contributes to steamy conditions in surrounding areas.
“It definitely increases humidity levels,” Roman explained. “Especially in rural areas and homes near cornfields.”
This natural effect may not raise temperatures directly, but it does amplify the perceived heat — pushing “feels like” conditions well beyond the actual temperature reading.
Storm Relief Possible Late Thursday
The good news? A break from the brutal heat could arrive late Thursday night, with an incoming cold front and storm system likely to reduce temperatures by Friday.
“Coverage of storms should be high enough to limit dangerous heat by Friday,” the NWS said, projecting a return to mid-80s by the weekend.
However, the pattern may stay stormy into the weekend, and any incoming system could carry heavy rainfall and potential for severe weather.
How are you preparing for the intense Chicago heat this week? Share your photos, tips, or cooling center recommendations at ChicagoMusicGuide.com.