S
M
T
W
T
F
S
30
81°
58°
31
82°
59°
1
82°
59°
2
81°
56°
3
76°
56°
4
81°
59°
5
78°
57°
6
75°
56°
7
75°
57°
8
76°
54°
9
75°
49°
10
73°
50°
11
75°
57°
12
81°
56°
13
79°
57°
14
73°
55°
15
78°
55°
16
78°
56°
17
Hist. Avg.
74°
56°
18
Hist. Avg.
74°
55°
19
Hist. Avg.
74°
55°
20
Hist. Avg.
73°
54°
21
Hist. Avg.
73°
54°
22
Hist. Avg.
73°
54°
23
Hist. Avg.
72°
54°
24
Hist. Avg.
72°
53°
25
Hist. Avg.
72°
53°
26
Hist. Avg.
71°
52°
27
Hist. Avg.
71°
52°
28
Hist. Avg.
70°
52°
29
Hist. Avg.
70°
51°
30
Hist. Avg.
70°
51°
1
Hist. Avg.
69°
50°
2
Hist. Avg.
69°
50°
3
Hist. Avg.
68°
50°
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 73° to 82°, with overnight lows between 49° and 59°. The average high for September is 78° with an average low of 56°. 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.
