S
M
T
W
T
F
S
30
81°
51°
31
80°
53°
1
81°
54°
2
78°
53°
3
79°
56°
4
84°
51°
5
78°
51°
6
79°
52°
7
79°
53°
8
77°
53°
9
78°
49°
10
77°
51°
11
78°
45°
12
76°
47°
13
76°
47°
14
77°
48°
15
75°
46°
16
75°
46°
17
74°
44°
18
74°
46°
19
77°
45°
20
75°
45°
21
74°
42°
22
73°
45°
23
79°
50°
24
70°
41°
25
69°
42°
26
Hist. Avg.
74°
40°
27
Hist. Avg.
74°
40°
28
Hist. Avg.
73°
40°
29
Hist. Avg.
73°
39°
30
Hist. Avg.
72°
39°
1
Hist. Avg.
72°
38°
2
Hist. Avg.
72°
38°
3
Hist. Avg.
71°
38°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
*Temporarily Unavailable
September Weather in Fort Collins
Fort Collins's September 2026 forecast shows daily high temperatures ranging from 69° to 84°, with overnight lows between 41° and 56°. 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.
