Illinois Frequent Weather Alerts: Blizzards, winter storms, flooding, tornadoes, thunderstorms.
Due to its 400 miles length and mid-continental positioning, Illinois has a climate that varies widely. Most of the State has humid, hot summers and cold winters. The southern portion has a more moderate winter.
One of the flattest states, there are no mountains to keep very cold Arctic air masses away in the winter or the humid air masses flowing in from the Gulf of Mexico in the summertime. Extreme cold and heat are not uncommon.
In the winter, wind chills can make the temperature seem much lower than it is; negative double digits happen annually and warnings are sent out to protect the vulnerable. In the summer, heat advisories warn people to stay indoors due to deadly temperatures. The humidity makes temperatures seem warmer than they are.
Flooding is common in the state and Illinois struggles with urban flooding caused by a combination of heavy rainfall and water-resistant roads.
Storms can happen during any season and severe thunderstorms are a normal part of the spring and early summer season. When severe enough, they can cause destructive tornadoes. Winter storms can bring heavy snowfall that can also lead to flooding if it melts too quickly.