S
M
T
W
T
F
S
30
69°
33°
31
66°
35°
1
70°
37°
2
72°
42°
3
77°
40°
4
75°
40°
5
75°
38°
6
63°
35°
7
68°
38°
8
69°
36°
9
65°
38°
10
64°
39°
11
62°
34°
12
62°
35°
13
61°
27°
14
62°
32°
15
67°
34°
16
70°
35°
17
70°
34°
18
67°
34°
19
66°
37°
20
70°
38°
21
69°
36°
22
66°
37°
23
67°
35°
24
70°
35°
25
70°
33°
26
61°
32°
27
54°
33°
28
58°
34°
29
57°
33°
30
58°
33°
1
57°
36°
2
65°
33°
3
56°
26°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Kalispell Northwest
Kalispell Northwest's September 2026 forecast shows daily high temperatures ranging from 54° to 77°, with overnight lows between 26° and 42°. The average high for September is 66° with an average low of 35°. 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 Kalispell Northwest. See also: October | November | December.
