S
M
T
W
T
F
S
30
87°
55°
31
86°
50°
1
80°
54°
2
79°
53°
3
78°
52°
4
79°
50°
5
77°
49°
6
77°
52°
7
82°
51°
8
83°
49°
9
78°
51°
10
76°
48°
11
75°
49°
12
76°
49°
13
74°
48°
14
75°
51°
15
79°
52°
16
82°
54°
17
82°
50°
18
81°
43°
19
72°
48°
20
76°
49°
21
80°
52°
22
79°
41°
23
78°
40°
24
69°
42°
25
70°
41°
26
75°
43°
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 87°, with overnight lows between 40° and 55°. The average high for September is 78° with an average low of 49°. 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.
