S
M
T
W
T
F
S
30
78°
66°
31
80°
65°
1
80°
58°
2
76°
58°
3
79°
62°
4
75°
63°
5
74°
63°
6
74°
61°
7
75°
57°
8
76°
54°
9
71°
55°
10
70°
63°
11
75°
60°
12
76°
62°
13
75°
62°
14
76°
61°
15
75°
62°
16
69°
53°
17
68°
53°
18
68°
52°
19
Hist. Avg.
71°
55°
20
Hist. Avg.
71°
54°
21
Hist. Avg.
70°
54°
22
Hist. Avg.
70°
54°
23
Hist. Avg.
69°
53°
24
Hist. Avg.
69°
53°
25
Hist. Avg.
69°
52°
26
Hist. Avg.
68°
52°
27
Hist. Avg.
68°
52°
28
Hist. Avg.
68°
51°
29
Hist. Avg.
67°
51°
30
Hist. Avg.
67°
50°
1
Hist. Avg.
66°
50°
2
Hist. Avg.
66°
50°
3
Hist. Avg.
66°
49°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
*Temporarily Unavailable
September Weather in Chicago
Chicago's September 2026 forecast shows daily high temperatures ranging from 68° to 80°, with overnight lows between 52° and 66°. The average high for September is 75° with an average low of 60°. 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.
