S
M
T
W
T
F
S
30
91°
67°
31
92°
67°
1
92°
66°
2
91°
67°
3
92°
68°
4
91°
67°
5
91°
65°
6
90°
59°
7
86°
57°
8
83°
60°
9
85°
61°
10
87°
63°
11
89°
62°
12
90°
64°
13
89°
66°
14
91°
65°
15
91°
63°
16
89°
62°
17
88°
64°
18
87°
65°
19
89°
64°
20
89°
59°
21
87°
63°
22
83°
63°
23
80°
59°
24
81°
63°
25
81°
62°
26
83°
59°
27
82°
59°
28
82°
62°
29
83°
57°
30
79°
61°
1
80°
63°
2
88°
62°
3
81°
61°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Rancho San Diego
Rancho San Diego's September 2026 forecast shows daily high temperatures ranging from 79° to 92°, with overnight lows between 57° and 68°. The average high for September is 87° with an average low of 63°. 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 San Diego. See also: October | November | December.
