S
M
T
W
T
F
S
30
52°
36°
31
54°
39°
1
55°
39°
2
57°
41°
3
61°
41°
4
61°
43°
5
64°
45°
6
68°
45°
7
55°
45°
8
61°
41°
9
59°
41°
10
59°
37°
11
55°
39°
12
59°
45°
13
64°
45°
14
50°
37°
15
55°
37°
16
55°
37°
17
48°
41°
18
50°
37°
19
45°
34°
20
45°
34°
21
50°
32°
22
N/A
23
45°
36°
24
43°
36°
25
43°
32°
26
48°
32°
27
54°
37°
28
N/A
29
43°
34°
30
37°
32°
1
52°
32°
2
66°
39°
3
68°
39°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
*Temporarily Unavailable
September Weather in Keystone
Keystone's September 2026 forecast shows daily high temperatures ranging from 66° to 68°, with overnight lows between 39° and 39°. The average high for September is 67° with an average low of 39°. 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 Keystone. See also: October | November | December.
