S
M
T
W
T
F
S
30
90°
71°
31
84°
66°
1
84°
58°
2
83°
57°
3
82°
58°
4
83°
61°
5
86°
67°
6
83°
65°
7
87°
63°
8
88°
62°
9
85°
60°
10
84°
60°
11
89°
62°
12
89°
60°
13
88°
61°
14
87°
58°
15
90°
62°
16
89°
61°
17
89°
60°
18
86°
57°
19
82°
56°
20
83°
57°
21
86°
58°
22
87°
59°
23
86°
58°
24
83°
55°
25
78°
52°
26
78°
53°
27
77°
51°
28
78°
52°
29
80°
54°
30
80°
56°
1
79°
53°
2
81°
55°
3
85°
59°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Rancho Santa Margarita
Rancho Santa Margarita's September 2026 forecast shows daily high temperatures ranging from 77° to 90°, with overnight lows between 51° and 67°. The average high for September is 84° with an average low of 58°. 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 Rancho Santa Margarita. See also: October | November | December.
