S
M
T
W
T
F
S
31
103°
65°
1
99°
65°
2
100°
67°
3
100°
70°
4
98°
68°
5
96°
61°
6
94°
56°
7
97°
59°
8
91°
58°
9
85°
57°
10
78°
59°
11
81°
59°
12
82°
58°
13
86°
57°
14
89°
57°
15
94°
60°
16
97°
60°
17
97°
67°
18
80°
64°
19
85°
68°
20
89°
62°
21
85°
58°
22
89°
59°
23
93°
64°
24
89°
65°
25
83°
61°
26
75°
63°
27
74°
63°
28
77°
62°
29
81°
57°
30
77°
60°
1
81°
55°
2
81°
54°
3
75°
62°
4
81°
52°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Castaic Junction
Castaic Junction's September 2025 forecast shows daily high temperatures ranging from ° to °, with overnight lows between ° and °. The average high for September is ° with an average low of °. 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 Castaic Junction. See also: October | November | December.
