"Temperatures are going to be falling into the 40s this afternoon," ABC7 Meteorologist Tracy Butler said.
This morning, weather is being blamed for a fatal crash on the Dan Ryan and may be a factor after a plane left the runway at O'Hare International Airport. Temperatures are expected to drop after the rain tapers off by early afternoon.
The heaviest rain was expected to last through the morning in the far northern suburbs. The weather comes on the heels of a wet month in the state.
Illinois' state climatologist says late-October rains helped restore soil moisture after three exceptionally dry months.
Climatologist Jim Angel says a near-normal 3.2 inches of precipitation fell in October, most of it in the last few days of the month.
Angel says the rains were heavy and widespread enough to help recharge soil that had been dried out in the previous three months. The long-term average rainfall for October is 3.26 inches.
Angel says precipitation was heaviest in Cook, Will, and Kankakee counties and in some areas of far southern Illinois. The largest amount was in Bourbonnais, which saw 6.79 inches of precipitation.
What's more, many areas of northern and central Illinois saw snow in October, with the most - 3.5 inches - reported in Mendota.
The Associated Press contributed to this report.