S
M
T
W
T
F
S
30
77°
55°
31
76°
55°
1
76°
56°
2
77°
54°
3
76°
54°
4
77°
55°
5
77°
60°
6
76°
58°
7
77°
58°
8
76°
56°
9
75°
53°
10
80°
52°
11
75°
51°
12
75°
52°
13
76°
51°
14
74°
57°
15
80°
58°
16
81°
59°
17
80°
57°
18
79°
49°
19
78°
48°
20
72°
49°
21
71°
54°
22
73°
55°
23
78°
55°
24
77°
56°
25
78°
46°
26
77°
44°
27
69°
46°
28
67°
45°
29
68°
45°
30
67°
43°
1
Hist. Avg.
72°
49°
2
Hist. Avg.
72°
48°
3
Hist. Avg.
71°
48°
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 67° to 81°, with overnight lows between 43° and 60°. The average high for September is 75° with an average low of 53°. 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.
