S
M
T
W
T
F
S
30
90°
71°
31
84°
66°
1
82°
63°
2
83°
57°
3
81°
58°
4
83°
61°
5
86°
67°
6
83°
68°
7
83°
63°
8
88°
62°
9
89°
60°
10
84°
59°
11
83°
59°
12
82°
58°
13
82°
59°
14
85°
58°
15
87°
57°
16
89°
61°
17
89°
60°
18
81°
55°
19
82°
56°
20
85°
58°
21
87°
60°
22
85°
60°
23
84°
59°
24
83°
57°
25
83°
59°
26
87°
60°
27
86°
61°
28
86°
60°
29
85°
60°
30
85°
59°
1
86°
60°
2
85°
59°
3
82°
57°
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 81° to 89°, with overnight lows between 55° and 68°. The average high for September is 85° with an average low of 60°. 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.
