S
M
T
W
T
F
S
30
84°
57°
31
87°
58°
1
86°
57°
2
87°
50°
3
83°
50°
4
81°
55°
5
86°
54°
6
85°
55°
7
83°
56°
8
86°
58°
9
86°
56°
10
85°
54°
11
84°
51°
12
78°
45°
13
73°
46°
14
76°
47°
15
79°
52°
16
76°
49°
17
74°
52°
18
78°
49°
19
71°
46°
20
73°
47°
21
72°
48°
22
69°
47°
23
67°
46°
24
69°
46°
25
72°
48°
26
77°
47°
27
76°
43°
28
68°
47°
29
76°
38°
30
74°
35°
1
64°
35°
2
64°
36°
3
65°
34°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Fort Collins
Fort Collins's September 2026 forecast shows daily high temperatures ranging from 64° to 87°, with overnight lows between 34° and 58°. The average high for September is 77° with an average low of 48°. 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 Collins. See also: October | November | December.
