S
M
T
W
T
F
S
30
77°
52°
31
79°
52°
1
81°
46°
2
77°
45°
3
74°
46°
4
76°
47°
5
81°
52°
6
83°
53°
7
84°
50°
8
77°
47°
9
75°
45°
10
75°
49°
11
77°
52°
12
82°
44°
13
81°
49°
14
78°
51°
15
83°
52°
16
82°
50°
17
81°
45°
18
71°
46°
19
73°
45°
20
79°
47°
21
78°
47°
22
79°
48°
23
77°
47°
24
77°
47°
25
75°
45°
26
73°
46°
27
76°
45°
28
75°
45°
29
75°
44°
30
74°
46°
1
75°
42°
2
70°
36°
3
64°
34°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Castle Rock
Castle Rock's September 2026 forecast shows daily high temperatures ranging from 64° to 84°, with overnight lows between 34° and 53°. The average high for September is 77° with an average low of 47°. 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.
