<P> Especially in the northern third of the state, intensive agriculture has made some species rare, while population numbers are increasing in the less - developed south . Large mammals generally no longer found in the wild in Illinois include American bison, gray wolf, American black bear, and elk . </P> <P> Illinois has a continental climate, with large temperature extremes not moderated by either mountains or oceans . Weather is influenced primarily by cold Canadian Arctic air in the winter, and warm, humid air from the Gulf of Mexico in the summer . High temperatures in the south of the state are about 10 to 12 ° F. warmer than the north . Average annual temperature is 47 ° F. in the north and 58 ° F. in the south . Temperatures greater than 90 ° F. occur about 45 days per year in the south, and 12 days per year in the north . Temperatures below zero ° F. occur one day or less per year in the south, and 12 days per year in the north . Annual rainfall is 34 inches (860 mm) in the north and 46 inches (1,200 mm) in the south . </P> <P> Prevailing winds are from the west . Average wind speeds "blowing off the prairie" are greater in the Chicago area . Statewide, the wind speeds average 8 to 12 miles per hour (13 to 19 km / h), and is greater in the winter than in summer . </P> <P> Snowfall averages 30 inches (760 mm) in the north and 10 inches (250 mm) in the south, although the actual snowfalls vary greatly by year . In some years, southern Illinois receives very little snowfall, and may never get typical winter weather . </P>

Why does the corn in illinois lean to the east