Thunderstorms, Hail Possible In Chicago Area: Weather Timeline

CHICAGO, IL — Isolated to scattered thunderstorms are expected Thursday, as well as another day of poor air quality, according to the National Weather Service.

The IEPA has issued an air pollution action day for Thursday for the greater Chicago metropolitan area. The air quality alert will be in effect until midnight.

"A Chicago area Air Pollution Action Day is declared when weather conditions are such that widespread ozone and or particulate levels are expected to be at or above the Unhealthy for Sensitive Groups category of the Air Quality Index for multiple days," according to the weather service.

Thursday also brings a limited thunderstorm risk, with a level 1 of 5 damaging wind risk and a level 1 of 5 large hail risk.

The weather service said isolated storms may develop late Thursday morning through the afternoon, with a greater potential for storms on Thursday evening and overnight.

The strongest storms could produce damaging winds and small hail, as well as torrential rainfall.

"Confidence in shower and storm timing and coverage remains low, so be sure to check back for updates through the day," the weather service advised.

Thursday will have a high of 90 degrees, and heat and humidity are on the rise with peak heat index values up to 100 degrees expected on both Friday and Saturday, according to the weather service.

Here is a look at the daily forecast through the weekend, per the weather service:

THURSDAY: A 20 percent chance of showers and thunderstorms after 4 p.m. Partly sunny, with a high near 90. Heat index values as high as 95. South wind 5 to 10 mph.

THURSDAY NIGHT: A 40 percent chance of showers and thunderstorms, mainly after 10 p.m. Mostly cloudy, with a low around 72. South wind 5 to 10 mph.

FRIDAY: A 20 percent chance of showers and thunderstorms before 1 p.m. Mostly cloudy, then gradually becoming sunny, with a high near 90. Heat index values as high as 98. South wind 10 to 15 mph, with gusts as high as 20 mph.

FRIDAY NIGHT: Mostly clear, with a low around 74. South wind around 10 mph, with gusts as high as 15 mph.

SATURDAY: Sunny, with a high near 92. South wind 10 to 15 mph, with gusts as high as 20 mph.

SATURDAY NIGHT: A 20 percent chance of showers and thunderstorms after 1 a.m. Partly cloudy, with a low around 75.

SUNDAY: A 30 percent chance of showers and thunderstorms, mainly after 1 p.m. Mostly sunny, with a high near 90.

SUNDAY NIGHT: A chance of showers and thunderstorms. Mostly cloudy, with a low around 72.