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
93°
61°
7
94°
64°
8
89°
60°
9
82°
56°
10
92°
50°
11
93°
51°
12
77°
53°
13
94°
61°
14
87°
52°
15
71°
50°
16
83°
59°
17
76°
55°
18
80°
52°
19
78°
50°
20
82°
51°
21
79°
50°
22
77°
53°
23
81°
54°
24
79°
51°
25
80°
52°
26
83°
46°
27
77°
50°
28
71°
50°
29
75°
45°
30
71°
47°
1
76°
47°
2
73°
48°
3
76°
44°
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 71° to 94°, with overnight lows between 44° and 61°. The average high for September is 79° with an average low of 51°. 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.
