S
M
T
W
T
F
S
30
104°
75°
31
99°
71°
1
97°
67°
2
99°
66°
3
100°
68°
4
102°
69°
5
101°
70°
6
94°
70°
7
98°
68°
8
100°
73°
9
98°
66°
10
90°
63°
11
97°
65°
12
98°
62°
13
93°
67°
14
92°
62°
15
93°
60°
16
88°
60°
17
82°
58°
18
78°
54°
19
79°
53°
20
82°
55°
21
84°
54°
22
80°
53°
23
79°
51°
24
82°
50°
25
80°
55°
26
79°
55°
27
76°
54°
28
76°
54°
29
78°
49°
30
80°
51°
1
83°
52°
2
83°
52°
3
82°
51°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Santa Rosa
Santa Rosa's September 2026 forecast shows daily high temperatures ranging from 76° to 98°, with overnight lows between 49° and 67°. The average high for September is 84° 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 Santa Rosa. See also: October | November | December.
