S
M
T
W
T
F
S
30
85°
66°
31
85°
66°
1
84°
65°
2
85°
65°
3
82°
64°
4
81°
65°
5
81°
64°
6
82°
63°
7
82°
64°
8
84°
65°
9
85°
65°
10
85°
66°
11
84°
65°
12
84°
64°
13
82°
65°
14
78°
63°
15
79°
61°
16
79°
64°
17
83°
63°
18
84°
62°
19
83°
61°
20
83°
61°
21
84°
60°
22
82°
58°
23
79°
59°
24
81°
62°
25
82°
64°
26
83°
65°
27
84°
65°
28
86°
64°
29
84°
61°
30
81°
58°
1
79°
57°
2
76°
57°
3
75°
55°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Rancho Bernardo
Rancho Bernardo's September 2026 forecast shows daily high temperatures ranging from 75° to 86°, with overnight lows between 55° and 66°. The average high for September is 82° 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 Bernardo. See also: October | November | December.
