Illinois should see its first frost sometime this month, if history is to be a guide. Typically, northern Illinois gets hit with frost in early October, for central Illinois its mid-October, and the southern parts of the state see the first frost later in the month, according to State Climatologist Jim Angel.
He notes they don't really measure frost.
Click here for Angel's comments
Angel says open areas are usually the first to experience frost. Homeowners can help protect their plants by covering them when frost is expected.