S
M
T
W
T
F
S
30
92°
72°
31
91°
71°
1
92°
71°
2
91°
70°
3
90°
70°
4
88°
69°
5
88°
70°
6
89°
68°
7
91°
65°
8
90°
66°
9
89°
68°
10
90°
67°
11
89°
68°
12
88°
67°
13
88°
67°
14
84°
65°
15
86°
66°
16
88°
65°
17
85°
63°
18
82°
62°
19
82°
61°
20
84°
63°
21
87°
65°
22
87°
64°
23
85°
64°
24
83°
63°
25
86°
64°
26
82°
63°
27
81°
63°
28
83°
62°
29
84°
62°
30
85°
60°
1
81°
61°
2
82°
60°
3
79°
61°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Helena
Helena's September 2026 forecast shows daily high temperatures ranging from 79° to 92°, with overnight lows between 60° and 72°. The average high for September is 86° 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 Helena. See also: October | November | December.
