S
M
T
W
T
F
S
31
90°
47°
1
92°
51°
2
90°
51°
3
89°
48°
4
65°
47°
5
72°
37°
6
83°
40°
7
87°
47°
8
84°
56°
9
83°
45°
10
81°
52°
11
74°
48°
12
81°
45°
13
80°
42°
14
83°
46°
15
75°
50°
16
72°
50°
17
77°
44°
18
79°
46°
19
81°
47°
20
88°
45°
21
86°
51°
22
66°
48°
23
80°
49°
24
88°
46°
25
88°
42°
26
74°
45°
27
83°
46°
28
70°
43°
29
87°
43°
30
74°
50°
1
73°
50°
2
75°
40°
3
63°
47°
4
60°
40°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Great Falls
Great Falls's September 2025 forecast shows daily high temperatures ranging from ° to °, with overnight lows between ° and °. The average high for September is ° with an average low of °. 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.
