S
M
T
W
T
F
S
30
67°
54°
31
66°
52°
1
66°
52°
2
65°
53°
3
65°
52°
4
64°
51°
5
65°
49°
6
64°
47°
7
64°
50°
8
63°
51°
9
65°
50°
10
64°
51°
11
64°
51°
12
62°
50°
13
63°
51°
14
65°
51°
15
64°
50°
16
64°
51°
17
63°
50°
18
60°
50°
19
62°
50°
20
60°
51°
21
60°
50°
22
61°
47°
23
Hist. Avg.
60°
49°
24
Hist. Avg.
59°
49°
25
Hist. Avg.
59°
49°
26
Hist. Avg.
59°
48°
27
Hist. Avg.
59°
48°
28
Hist. Avg.
59°
48°
29
Hist. Avg.
59°
48°
30
Hist. Avg.
59°
48°
1
Hist. Avg.
58°
48°
2
Hist. Avg.
58°
48°
3
Hist. Avg.
58°
48°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
*Temporarily Unavailable
September Weather in Castleside
Castleside's September 2026 forecast shows daily high temperatures ranging from 60° to 67°, with overnight lows between 47° and 54°. The average high for September is 64° 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 Castleside. See also: October | November | December.
