S
M
T
W
T
F
S
30
76°
47°
31
76°
49°
1
75°
55°
2
74°
56°
3
74°
54°
4
73°
52°
5
74°
49°
6
73°
48°
7
74°
47°
8
75°
49°
9
74°
47°
10
76°
46°
11
77°
51°
12
71°
47°
13
73°
54°
14
73°
49°
15
Hist. Avg.
76°
50°
16
Hist. Avg.
76°
50°
17
Hist. Avg.
76°
50°
18
Hist. Avg.
75°
49°
19
Hist. Avg.
75°
49°
20
Hist. Avg.
75°
49°
21
Hist. Avg.
74°
49°
22
Hist. Avg.
74°
49°
23
Hist. Avg.
74°
49°
24
Hist. Avg.
74°
48°
25
Hist. Avg.
73°
48°
26
Hist. Avg.
73°
48°
27
Hist. Avg.
72°
48°
28
Hist. Avg.
72°
48°
29
Hist. Avg.
72°
48°
30
Hist. Avg.
71°
47°
1
Hist. Avg.
71°
47°
2
Hist. Avg.
70°
47°
3
Hist. Avg.
70°
47°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
*Temporarily Unavailable
September Weather in Castle Rock
Castle Rock's September 2026 forecast shows daily high temperatures ranging from 71° to 77°, with overnight lows between 46° and 56°. The average high for September is 74° with an average low of 50°. 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 Castle Rock. See also: October | November | December.
