The first fall freeze, with lows of 32 degrees or colder, typically occurs during the first half of October in central Illinois. Click here to monitor the occurrence of this year's first freeze. (click image to enlarge)
Clouds were not formally named and classified until the early 19th century. Clouds were classified using Latin words to describe how the clouds appear to a ground observer. The initial classification had four basic cloud types; this was expanded in 1887 to also account for the height of the clouds above the ground, or their vertical appearance. This system of grouping cloud types is still in use today.