S
M
T
W
T
F
S
30
74°
67°
31
74°
66°
1
75°
69°
2
77°
70°
3
75°
70°
4
81°
71°
5
81°
70°
6
79°
69°
7
78°
68°
8
73°
67°
9
74°
68°
10
72°
69°
11
74°
68°
12
74°
66°
13
76°
67°
14
77°
67°
15
78°
66°
16
76°
66°
17
75°
65°
18
75°
66°
19
73°
65°
20
75°
66°
21
77°
61°
22
77°
58°
23
76°
52°
24
68°
51°
25
70°
58°
26
74°
54°
27
69°
61°
28
73°
63°
29
76°
63°
30
75°
58°
1
76°
51°
2
65°
58°
3
64°
57°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Chicago
Chicago's September 2026 forecast shows daily high temperatures ranging from 64° to 81°, with overnight lows between 51° and 71°. The average high for September is 74° with an average low of 64°. AccuWeather's monthly forecast extends further ahead than any other source, with day-by-day RealFeel® Temperatures giving a complete picture of how September weather will actually feel in Chicago. See also: October | November | December.
