S
M
T
W
T
F
S
30
93°
69°
31
94°
71°
1
93°
69°
2
93°
69°
3
92°
70°
4
92°
65°
5
91°
70°
6
93°
68°
7
92°
69°
8
91°
68°
9
91°
69°
10
92°
69°
11
91°
68°
12
88°
68°
13
85°
67°
14
86°
67°
15
85°
66°
16
87°
67°
17
85°
66°
18
85°
65°
19
86°
63°
20
84°
60°
21
82°
60°
22
83°
61°
23
85°
63°
24
86°
64°
25
87°
65°
26
86°
64°
27
87°
64°
28
82°
61°
29
82°
58°
30
85°
61°
1
81°
56°
2
Hist. Avg.
79°
58°
3
Hist. Avg.
79°
58°
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 81° to 94°, with overnight lows between 56° and 71°. The average high for September is 88° 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.
