S
M
T
W
T
F
S
26
63°
51°
27
64°
49°
28
75°
42°
29
78°
46°
30
81°
47°
1
84°
52°
2
85°
51°
3
72°
52°
4
69°
50°
5
68°
48°
6
79°
56°
7
85°
58°
8
81°
56°
9
78°
59°
10
81°
57°
11
81°
57°
12
82°
58°
13
85°
60°
14
80°
54°
15
75°
50°
16
75°
52°
17
76°
52°
18
76°
51°
19
77°
52°
20
77°
54°
21
83°
57°
22
84°
58°
23
84°
58°
24
83°
57°
25
84°
58°
26
84°
58°
27
82°
57°
28
81°
55°
29
80°
54°
30
78°
52°
31
78°
52°
1
79°
53°
2
81°
55°
3
82°
56°
4
85°
57°
5
83°
57°
6
83°
56°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
May Weather in Castaic Junction
Castaic Junction's May 2026 forecast shows daily high temperatures ranging from 68° to 85°, with overnight lows between 48° and 60°. The average high for May is 80° with an average low of 55°. AccuWeather's monthly forecast extends further ahead than any other source, with day-by-day RealFeel® Temperatures giving a complete picture of how May weather will actually feel in Castaic Junction. See also: June | July | August.
