S
M
T
W
T
F
S
30
72°
54°
31
76°
54°
1
76°
57°
2
72°
53°
3
70°
53°
4
71°
54°
5
71°
55°
6
72°
54°
7
73°
53°
8
72°
56°
9
71°
57°
10
72°
59°
11
73°
58°
12
74°
59°
13
74°
61°
14
78°
60°
15
78°
59°
16
79°
58°
17
78°
58°
18
78°
57°
19
77°
57°
20
76°
58°
21
77°
59°
22
78°
59°
23
77°
58°
24
74°
59°
25
70°
58°
26
69°
57°
27
70°
58°
28
71°
59°
29
72°
58°
30
71°
59°
1
74°
56°
2
72°
56°
3
76°
59°
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 79°, with overnight lows between 53° and 61°. The average high for September is 74° with an average low of 57°. 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.
