Chicago First Alert Weather: Warm July 4 weekend, shower chances ahead

CHICAGO (CBS)-- The air quality has greatly improved for most of the area. 

An Air Quality Alert remains in effect for Northwest Indiana until Midnight.  

Temperatures are climbing to the low 90s Friday with high humidity and a slight chance for a late-day shower. 

Saturday is the first day of NASCAR and the course may be wet due to light rain showers. The best chance for thunderstorms Saturday is early morning and then again late afternoon and evening. 

Showers and thunderstorms are possible again Sunday late in the day.