S
M
T
W
T
F
S
30
72°
57°
31
75°
59°
1
76°
59°
2
76°
58°
3
72°
59°
4
71°
59°
5
75°
58°
6
77°
59°
7
77°
58°
8
76°
58°
9
76°
56°
10
72°
52°
11
71°
52°
12
72°
53°
13
71°
55°
14
70°
54°
15
73°
53°
16
75°
56°
17
74°
59°
18
77°
60°
19
69°
60°
20
70°
59°
21
76°
59°
22
77°
58°
23
74°
59°
24
75°
59°
25
77°
58°
26
76°
59°
27
77°
58°
28
71°
58°
29
71°
59°
30
72°
59°
1
77°
58°
2
78°
59°
3
77°
58°
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 69° to 78°, with overnight lows between 52° and 60°. The average high for September is 74° with an average low of 58°. 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.
