S
M
T
W
T
F
S
30
93°
64°
31
98°
63°
1
100°
72°
2
98°
74°
3
97°
72°
4
99°
75°
5
97°
72°
6
93°
67°
7
90°
69°
8
89°
63°
9
88°
66°
10
86°
64°
11
83°
58°
12
82°
58°
13
83°
59°
14
85°
68°
15
81°
65°
16
83°
64°
17
83°
64°
18
84°
63°
19
83°
65°
20
84°
64°
21
83°
64°
22
83°
63°
23
82°
62°
24
83°
62°
25
83°
62°
26
82°
62°
27
83°
61°
28
82°
61°
29
81°
60°
30
81°
60°
1
80°
58°
2
80°
60°
3
79°
59°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Bethalto
Bethalto's September 2026 forecast shows daily high temperatures ranging from 79° to 100°, with overnight lows between 58° and 75°. The average high for September is 86° with an average low of 64°. 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 Bethalto. See also: October | November | December.
