S
M
T
W
T
F
S
30
82°
68°
31
91°
70°
1
94°
70°
2
94°
72°
3
92°
69°
4
90°
70°
5
88°
66°
6
82°
62°
7
79°
60°
8
76°
59°
9
79°
60°
10
79°
55°
11
76°
53°
12
77°
53°
13
76°
56°
14
78°
54°
15
79°
59°
16
81°
59°
17
80°
58°
18
80°
59°
19
79°
59°
20
81°
58°
21
81°
59°
22
80°
58°
23
80°
58°
24
79°
57°
25
80°
58°
26
80°
57°
27
79°
56°
28
79°
56°
29
78°
55°
30
77°
55°
1
77°
54°
2
76°
54°
3
77°
53°
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 76° to 94°, with overnight lows between 53° and 72°. The average high for September is 81° with an average low of 59°. 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.
