S
M
T
W
T
F
S
30
89°
58°
31
89°
58°
1
88°
57°
2
88°
57°
3
87°
56°
4
85°
56°
5
83°
55°
6
85°
55°
7
85°
54°
8
76°
54°
9
79°
55°
10
77°
53°
11
85°
54°
12
84°
55°
13
76°
52°
14
76°
51°
15
78°
52°
16
76°
50°
17
81°
48°
18
73°
49°
19
74°
50°
20
77°
48°
21
79°
45°
22
73°
43°
23
72°
43°
24
71°
44°
25
72°
47°
26
80°
45°
27
74°
43°
28
70°
48°
29
78°
41°
30
76°
42°
1
72°
44°
2
76°
47°
3
77°
44°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Mission Viejo
Mission Viejo's September 2026 forecast shows daily high temperatures ranging from 70° to 89°, with overnight lows between 41° and 58°. The average high for September is 79° with an average low of 50°. 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 Mission Viejo. See also: October | November | December.
