Illinois severe thunderstorm warnings

What a severe thunderstorm warning means

The National Weather Service calls a thunderstorm severe when it produces hail at least one inch in diameter (about the size of a quarter), wind gusts of at least 58 mph, or a tornado. A severe thunderstorm warning is issued for the storm itself and the area in its path, usually for 30 to 60 minutes.

More about severe thunderstorm warnings and the national map →

What to do

• Move indoors to a sturdy building and stay away from windows.
• Park vehicles in a garage or under cover if hail is expected and there is time.
• Avoid driving into the storm core, where hail and downed trees are worst.
• Be ready to shelter if a tornado warning follows.