S
M
T
W
T
F
S
30
65°
43°
31
67°
48°
1
64°
46°
2
57°
49°
3
62°
47°
4
62°
35°
5
70°
44°
6
72°
50°
7
71°
45°
8
75°
49°
9
59°
50°
10
58°
49°
11
59°
44°
12
67°
36°
13
58°
48°
14
58°
32°
15
46°
31°
16
49°
28°
17
61°
33°
18
59°
41°
19
71°
44°
20
73°
44°
21
69°
48°
22
65°
37°
23
59°
42°
24
54°
34°
25
59°
35°
26
59°
32°
27
52°
34°
28
55°
36°
29
52°
33°
30
51°
34°
1
50°
36°
2
46°
29°
3
40°
34°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Fort Simpson
Fort Simpson's September 2026 forecast shows daily high temperatures ranging from 40° to 65°, with overnight lows between 29° and 42°. The average high for September is 54° 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 Fort Simpson. See also: October | November | December.
