S
M
T
W
T
F
S
30
82°
64°
31
82°
63°
1
84°
61°
2
77°
56°
3
76°
56°
4
76°
57°
5
78°
56°
6
82°
61°
7
84°
63°
8
84°
62°
9
83°
63°
10
84°
62°
11
82°
61°
12
84°
62°
13
84°
63°
14
82°
55°
15
72°
54°
16
72°
56°
17
75°
54°
18
71°
53°
19
72°
48°
20
71°
51°
21
79°
53°
22
79°
54°
23
80°
48°
24
73°
48°
25
71°
50°
26
75°
55°
27
76°
56°
28
77°
52°
29
68°
45°
30
67°
45°
1
67°
49°
2
74°
48°
3
76°
52°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Montana
Montana's September 2026 forecast shows daily high temperatures ranging from 67° to 84°, with overnight lows between 45° and 64°. The average high for September is 77° with an average low of 55°. 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.
