Illinois September Weather

Illinois weather averages and all-time records in the month of September from 1991–2020 based on data made available by the NOAA.

State:

Month:

Statewide September Averages
High temperature	78.5 °F
Low temperature	55.0 °F
Precipitation	3.4 inches

Illinois Cities

September weather averages for various places in Illinois, from 1991–2020.

City	Average (°F)		Record (°F)		Monthly (inches)
City	High	Low	High	Low	Precipitation
Aledo	76.1	52.8	102	24	3.6
Aurora	76.2	54.5	103	24	3.4
Belleville	83.0	57.3	103	26	3.4
Bloomington-Normal	78.4	53.3	103	22	3.2
Carbondale	81.3	56.0	108	20	3.2
Carlyle	80.0	57.9	105	30	3.7
Champaign	78.9	54.6	101	29	3.2
Charleston	80.1	56.5	104	25	3.2
Chicago	76.1	58.7	101	33	3.3
Danville	78.8	55.4	102	22	3.2
Decatur	79.3	57.1	104	20	3.1
Dixon	75.3	52.7	102	22	3.9
Du Quoin	80.7	57.0	108	27	3.4
Elgin	75.5	52.8	99	25	3.6
Elizabeth	74.8	49.9	97	19	3.8
Fairfield	81.5	56.5	105	25	2.9
Freeport	74.6	51.0	101	23	4.1
Galesburg	76.4	55.3	100	19	3.8
Geneseo	76.8	55.0	99	24	3.6
Hoopeston	78.6	55.2	103	25	3.4
Jacksonville	80.0	53.3	106	23	3.5
Joliet	76.5	55.3	101	28	3.2
Kankakee	77.9	54.2	100	27	2.6
Kewanee	75.8	51.5	102	25	3.5
Lincoln	79.2	53.1	104	22	3.3
Moline	77.4	54.2	100	30	3.3
Monmouth	78.5	54.3	103	18	3.9
Morris	78.1	55.3	103	26	3.5
Morrison	76.5	51.1	103	19	3.4
Mt. Vernon	78.9	56.0	105	23	3.0
Olney	81.0	56.5	106	27	3.3
Ottawa	77.4	54.2	103	25	3.3
Pana	81.0	55.3	105	26	3.4
Paris	78.5	55.7	105	24	3.0
Peoria	77.8	56.1	102	26	3.5
Quincy	78.0	56.1	105	26	3.0
Rantoul	80.0	53.7	103	24	3.3
Rockford	75.4	53.0	103	24	3.6
Springfield	79.8	55.4	102	32	2.9
Tuscola	79.5	55.7	103	21	3.2