S
M
T
W
T
F
S
30
77°
51°
31
77°
51°
1
76°
50°
2
77°
51°
3
76°
52°
4
75°
50°
5
75°
47°
6
76°
42°
7
69°
40°
8
68°
42°
9
68°
44°
10
72°
46°
11
74°
45°
12
75°
46°
13
73°
48°
14
75°
48°
15
74°
42°
16
73°
43°
17
72°
45°
18
73°
47°
19
72°
45°
20
72°
40°
21
70°
45°
22
65°
44°
23
62°
40°
24
64°
44°
25
64°
42°
26
68°
40°
27
64°
40°
28
64°
43°
29
65°
37°
30
62°
43°
1
62°
45°
2
68°
43°
3
62°
42°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Mount San Jacinto State Park
Mount San Jacinto State Park's September 2026 forecast shows daily high temperatures ranging from 62° to 77°, with overnight lows between 37° and 52°. The average high for September is 70° with an average low of 45°. 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 Mount San Jacinto State Park. See also: October | November | December.
