A line of storms racing toward Chicago prompted Severe Thunderstorm Warnings for most area counties Wednesday afternoon. The greatest severe weather threat is hail, wind and isolated tornadoes.

The possible hazards include damaging winds, large hail, an isolated tornado, and torrential downpours. Dew points and moisture levels are high, meaning storms could quickly drop 1–2 inches of rain, leading to a flash flooding threat in some areas.

A Severe Thunderstorm Watch has been issued for Boone, Cook, DeKalb, DuPage, Grundy, Kane, Kankakee, Kendall, LaSalle, Lake, McHenry and Will counties in Illinois and Lake and Porter counties in Indiana until 8 p.m. Wednesday will be very hot and humid, with highs in the low 90s.