Temperatures to soar to mid-90s Thursday, followed by possibly severe thunderstorms, flash flooding

Highs in the upper 70s and lower 80s were expected on Wednesday in the Chicago area before warmer weather Thursday and a chance of thunderstorms Thursday night and Friday, according to forecasters.

Separately, the National Weather Service has an air quality advisory in effect until 4 p.m. Wednesday for the Rockton area, following a massive fire at a chemical plant there.

There is a low chance for thunderstorms Thursday morning with temperatures in the upper 80s and lower 90s. Humid conditions will result in higher heat indices in the mid-90s to near 100 in the afternoon, according to the weather service.

Thunderstorms and showers are forecast for Thursday evening and overnight north of interstate 88 with a potential of isolated flash flooding, said Brian Leatherwood of the weather service’s Chicago-area office. Some storms could get severe with strong winds and hail, he added.

The record high for June 17 is 96 degrees, set in 1957, according to the weather service.

Friday will see similar conditions with temperatures in the mid-90s and a possibility of additional thunderstorms in areas south of Interstate 80.

“We can see the sort of weather you expect in the summertime: thunderstorm activity due to the mugginess,” Leatherwood said.

The Rockton area was under the air quality alert at least until 4 p.m. The Illinois Environmental Protection Agency issued this alert:

“Out of an abundance of caution, while air quality monitoring and analysis continues, it is recommended that individuals continue wearing a protective face covering to reduce exposure to particulate matter in the air.”

For more details and an updated forecast, check the Tribune’s weather page.