S
M
T
W
T
F
S
30
71°
58°
31
67°
58°
1
71°
61°
2
73°
62°
3
72°
60°
4
72°
58°
5
74°
58°
6
72°
59°
7
83°
56°
8
87°
61°
9
94°
66°
10
85°
60°
11
73°
60°
12
71°
60°
13
71°
59°
14
78°
56°
15
73°
56°
16
66°
58°
17
72°
60°
18
69°
58°
19
68°
57°
20
64°
57°
21
68°
58°
22
67°
57°
23
78°
55°
24
77°
59°
25
71°
58°
26
69°
56°
27
65°
58°
28
70°
53°
29
75°
55°
30
77°
55°
1
73°
57°
2
72°
56°
3
79°
60°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in South San Francisco
South San Francisco's September 2026 forecast shows daily high temperatures ranging from 70° to 79°, with overnight lows between 53° and 60°. The average high for September is 74° with an average low of 56°. 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 South San Francisco. See also: October | November | December.
