S
M
T
W
T
F
S
30
83°
69°
31
87°
71°
1
95°
77°
2
95°
76°
3
92°
74°
4
90°
74°
5
86°
70°
6
81°
66°
7
84°
70°
8
86°
71°
9
87°
66°
10
81°
65°
11
77°
61°
12
77°
62°
13
76°
60°
14
77°
61°
15
81°
56°
16
80°
63°
17
79°
62°
18
72°
62°
19
76°
62°
20
77°
61°
21
76°
62°
22
75°
60°
23
72°
59°
24
73°
57°
25
76°
59°
26
76°
54°
27
66°
50°
28
64°
47°
29
65°
50°
30
64°
48°
1
63°
49°
2
67°
56°
3
65°
55°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in O'Hare
O'Hare's September 2026 forecast shows daily high temperatures ranging from 63° to 95°, with overnight lows between 47° and 76°. The average high for September is 77° with an average low of 61°. 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 O'Hare. See also: October | November | December.
