The length of Illinois is 390 miles and has a varied climate. Most of the state experiences a humid continental climate. It has hot summers and cold winters. The southern portion has a humid tropical climate. Precipitation too varies with 48 inches in the southern region and 35 inches toward the north. In Chicago, the average snowfall is over 38 inches while in the south, it is below 14 inches. Thunderstorms are common here with about 50 days of thunderstorms per year. Tornadoes are also common and deadly. The most destructive tornado, Tri-State Tornado, was recorded in Illinois. On average, the state receives 35 tornadoes per year. However, the climate here changes quickly. It is tough to predict the weather here.