CHICAGO (CBS) -- An Air Quality Alert is in effect until midnight Friday night, due to increased ozone pollution. 

The air quality is expected to be in the "Unhealthy for Sensitive Groups" category; meaning people with medical conditions such as heart and lung disease or diabetes, older adults, and children could suffer health issues when engaging in outdoor activities. 

It will be mostly sunny and hot for Friday, with highs near 90 degrees. A lake breeze will keep lakeside locations cooler, in the upper 70s and low 80s. 

Most locations will remain dry, although a spotty shower in the far western suburbs in possible. Temperatures will cool quickly for lakeside locations Friday evening, with temperatures in the upper 50s by 11 p.m.

Morning clouds will give way to a sunny afternoon for both Saturday and Sunday. 

Highs will be in the mid 80s, with cooler conditions near the lake.

A front arrives on Monday allowing for a chance of isolated showers. Highs in the low to mid 80s on Monday, then in the low 70s for Tuesday through Thursday.

THIS AFTERNOON: Mostly sunny and hot. High 90°, but 70s and 80s near the lake.

TONIGHT: Mostly clear skies. Low 64°.

SATURDAY: Sunny afternoon. High 87°, upper 70s near the lake.

SUNDAY: Morning clouds, then mostly sunny in the afternoon. High 84°, mid to upper 70s near the lake.