S
M
T
W
T
F
S
30
89°
65°
31
90°
66°
1
91°
70°
2
92°
69°
3
88°
70°
4
87°
69°
5
89°
69°
6
89°
68°
7
90°
69°
8
90°
69°
9
89°
68°
10
90°
69°
11
90°
69°
12
89°
66°
13
89°
61°
14
82°
60°
15
81°
60°
16
81°
61°
17
82°
63°
18
86°
66°
19
86°
65°
20
80°
66°
21
86°
65°
22
87°
64°
23
86°
58°
24
79°
57°
25
77°
55°
26
80°
56°
27
82°
55°
28
Hist. Avg.
81°
57°
29
Hist. Avg.
81°
56°
30
Hist. Avg.
81°
56°
1
Hist. Avg.
80°
56°
2
Hist. Avg.
80°
55°
3
Hist. Avg.
80°
55°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
*Temporarily Unavailable
September Weather in Montana
Montana's September 2026 forecast shows daily high temperatures ranging from 77° to 92°, with overnight lows between 55° and 70°. 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 Montana. See also: October | November | December.
