S
M
T
W
T
F
S
30
83°
63°
31
89°
58°
1
90°
59°
2
93°
55°
3
94°
55°
4
96°
57°
5
97°
59°
6
90°
63°
7
87°
61°
8
89°
56°
9
84°
54°
10
94°
59°
11
94°
56°
12
87°
51°
13
78°
50°
14
77°
54°
15
82°
57°
16
87°
57°
17
83°
54°
18
82°
55°
19
84°
52°
20
67°
49°
21
80°
53°
22
79°
52°
23
78°
51°
24
74°
51°
25
70°
50°
26
71°
48°
27
76°
50°
28
73°
47°
29
70°
39°
30
61°
36°
1
62°
36°
2
61°
35°
3
63°
36°
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 61° to 94°, with overnight lows between 35° and 63°. The average high for September is 78° with an average low of 50°. 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.
