S
M
T
W
T
F
S
30
85°
67°
31
81°
66°
1
81°
63°
2
79°
61°
3
79°
56°
4
79°
61°
5
91°
59°
6
93°
73°
7
98°
74°
8
98°
75°
9
100°
77°
10
95°
74°
11
91°
70°
12
83°
66°
13
80°
66°
14
79°
62°
15
80°
64°
16
77°
67°
17
76°
65°
18
80°
63°
19
77°
62°
20
77°
64°
21
77°
64°
22
75°
64°
23
76°
63°
24
79°
64°
25
81°
63°
26
78°
65°
27
78°
63°
28
79°
64°
29
74°
60°
30
72°
61°
1
77°
62°
2
74°
61°
3
73°
62°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in San Ysidro
San Ysidro's September 2026 forecast shows daily high temperatures ranging from 72° to 81°, with overnight lows between 60° and 65°. The average high for September is 77° 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 San Ysidro. See also: October | November | December.
