S
M
T
W
T
F
S
30
91°
59°
31
89°
61°
1
92°
60°
2
93°
60°
3
91°
59°
4
90°
60°
5
91°
58°
6
91°
54°
7
90°
59°
8
88°
59°
9
90°
58°
10
92°
58°
11
90°
57°
12
90°
57°
13
87°
58°
14
88°
57°
15
88°
54°
16
89°
51°
17
81°
55°
18
81°
55°
19
82°
46°
20
80°
46°
21
78°
47°
22
79°
48°
23
80°
50°
24
84°
52°
25
84°
53°
26
86°
51°
27
86°
54°
28
85°
48°
29
83°
48°
30
78°
52°
1
83°
49°
2
86°
51°
3
83°
52°
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 78° to 93°, with overnight lows between 46° and 61°. The average high for September is 86° with an average low of 54°. 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.
