S
M
T
W
T
F
S
30
85°
66°
31
84°
66°
1
84°
67°
2
87°
66°
3
85°
70°
4
88°
69°
5
88°
68°
6
87°
65°
7
85°
69°
8
86°
69°
9
84°
67°
10
82°
67°
11
86°
66°
12
86°
68°
13
85°
67°
14
86°
67°
15
86°
66°
16
85°
67°
17
85°
66°
18
84°
65°
19
83°
64°
20
84°
60°
21
82°
64°
22
80°
65°
23
83°
63°
24
83°
62°
25
82°
59°
26
83°
62°
27
82°
63°
28
82°
61°
29
81°
60°
30
81°
61°
1
79°
60°
2
81°
60°
3
75°
61°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Grant Park
Grant Park's September 2026 forecast shows daily high temperatures ranging from 75° to 88°, with overnight lows between 59° and 70°. The average high for September is 84° with an average low of 65°. 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 Grant Park. See also: October | November | December.
