S
M
T
W
T
F
S
30
87°
70°
31
86°
69°
1
94°
74°
2
92°
73°
3
92°
70°
4
91°
70°
5
81°
68°
6
83°
61°
7
81°
59°
8
86°
57°
9
89°
66°
10
88°
71°
11
79°
66°
12
80°
66°
13
90°
72°
14
79°
59°
15
77°
52°
16
85°
58°
17
87°
66°
18
84°
72°
19
76°
67°
20
82°
62°
21
73°
62°
22
68°
55°
23
60°
54°
24
63°
54°
25
67°
52°
26
68°
53°
27
67°
51°
28
70°
53°
29
73°
55°
30
75°
54°
1
74°
51°
2
73°
57°
3
66°
56°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Great Falls
Great Falls's September 2026 forecast shows daily high temperatures ranging from 60° to 82°, with overnight lows between 51° and 67°. The average high for September is 70° with an average low of 56°. 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 Great Falls. See also: October | November | December.
