S
M
T
W
T
F
S
30
95°
63°
31
100°
65°
1
102°
74°
2
101°
74°
3
101°
74°
4
99°
73°
5
97°
73°
6
95°
71°
7
90°
72°
8
90°
67°
9
88°
71°
10
88°
67°
11
86°
61°
12
83°
62°
13
85°
63°
14
81°
60°
15
82°
66°
16
84°
65°
17
84°
65°
18
85°
64°
19
84°
65°
20
85°
65°
21
84°
64°
22
84°
64°
23
83°
63°
24
84°
63°
25
83°
62°
26
84°
61°
27
83°
62°
28
83°
62°
29
82°
61°
30
82°
61°
1
81°
60°
2
81°
61°
3
80°
60°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Granite City
Granite City's September 2026 forecast shows daily high temperatures ranging from 80° to 102°, with overnight lows between 60° and 74°. The average high for September is 87° 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 Granite City. See also: October | November | December.
