CHICAGO (CBS) — Hot and humid conditions in the Chicago area on Tuesday could spark a severe thunderstorm by the end of the day, before giving way to much milder conditions on Wednesday.

CBS 2 Meteorologist Megan Glaros reports highs will be in the low 90s. If the mercury hits 92 degrees, that would make it the hottest day of the year so far. The previous high this year was 91 on June 17.

“A combination of afternoon temperatures in the lower 90s and high dew points on Tuesday will result in maximum heat index values between 95 to 100 degrees,” the National Weather Service said in a special weather statement for the Chicago area. “Heat safety precautions should be taken for those at risk to heat related illnesses, or if you will be spending prolonged periods of time outdoors.”

Thunderstorms are likely to fire up sometime between 7 p.m. and 11 p.m. Tuesday, with a risk of severe storms stretching from southwestern Michigan and southeastern Wisconsin to southeastern Nebraska and northeastern Kansas.

The wet weather should be gone by early Wednesday morning, and send temperatures dipping to the low 60s overnight, with highs in the upper 70s on Wednesday and Thursday.