Illinois Suddenly in Storm Danger Zone This Weekend

We've known that weekend thunderstorms would likely impact the Midwest this weekend, but the new updated outlook now includes Illinois in the danger zone for severe thunderstorm development.

As we get closer to the weekend, NOAA's Storm Prediction Center has updated their convective outlook for Saturday, October 18, 2025 and expanded the advisory areas to include nearly all of Illinois now. While most of the state is only in a marginal risk area for severe thunderstorm development, there is an area in the extreme southwestern part of Illinois that is in the yellow slight risk region.

What does this thunderstorm advisory for Illinois mean?

The green marginal area has a 5% chance of seeing a severe thunderstorm impact an area within 25 miles. The yellow slight risk area has a 15% chance of seeing a severe thunderstorm within 25 miles. The NOAA Storm Prediction Center says this area has the  "greatest potential for tornadoes...Supercells should also be capable of large hail". Damaging wind gusts are also expected to be a key part of the storms as they move across Missouri and Illinois. In his discussion about the incoming storms this weekend, Ryan Hall just highlighted how unstable the atmosphere is expected to be.

As of now, the most dangerous storm development is expected to be Saturday afternoon into Saturday evening, but that will depend on when this system moves through the Midwest. Just make sure you're weather aware this weekend and have multiple ways to receive warnings if/when they are issued by the National Weather Service.