S
M
T
W
T
F
S
30
93°
68°
31
88°
59°
1
85°
56°
2
84°
54°
3
82°
56°
4
83°
59°
5
89°
56°
6
70°
65°
7
93°
65°
8
88°
67°
9
105°
67°
10
101°
74°
11
95°
71°
12
90°
66°
13
88°
63°
14
89°
60°
15
82°
61°
16
80°
66°
17
81°
61°
18
82°
54°
19
86°
52°
20
84°
59°
21
80°
62°
22
87°
55°
23
97°
60°
24
97°
63°
25
94°
63°
26
94°
58°
27
90°
57°
28
89°
65°
29
93°
65°
30
93°
66°
1
96°
65°
2
89°
64°
3
91°
66°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Castaic Junction
Castaic Junction's September 2026 forecast shows daily high temperatures ranging from 89° to 97°, with overnight lows between 57° and 66°. The average high for September is 93° with an average low of 63°. 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.
