S
M
T
W
T
F
S
30
68°
33°
31
69°
34°
1
75°
38°
2
77°
40°
3
79°
41°
4
79°
39°
5
66°
31°
6
65°
36°
7
68°
36°
8
69°
39°
9
71°
37°
10
69°
31°
11
67°
34°
12
67°
37°
13
66°
34°
14
64°
29°
15
62°
28°
16
61°
26°
17
61°
27°
18
62°
28°
19
62°
33°
20
66°
32°
21
69°
29°
22
61°
27°
23
59°
26°
24
58°
25°
25
57°
26°
26
58°
27°
27
56°
25°
28
57°
27°
29
63°
28°
30
56°
23°
1
67°
36°
2
68°
34°
3
Hist. Avg.
58°
33°
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 56° to 79°, with overnight lows between 23° and 41°. The average high for September is 65° with an average low of 32°. 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.
