S
M
T
W
T
F
S
30
82°
48°
31
70°
49°
1
73°
58°
2
73°
56°
3
68°
59°
4
75°
54°
5
79°
48°
6
79°
48°
7
92°
52°
8
97°
59°
9
100°
59°
10
100°
56°
11
89°
57°
12
87°
55°
13
82°
54°
14
81°
55°
15
83°
52°
16
85°
54°
17
88°
55°
18
89°
54°
19
83°
51°
20
84°
55°
21
76°
53°
22
77°
52°
23
79°
53°
24
79°
52°
25
80°
51°
26
76°
54°
27
82°
54°
28
83°
54°
29
84°
55°
30
83°
54°
1
84°
54°
2
84°
53°
3
83°
53°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Petaluma
Petaluma's September 2026 forecast shows daily high temperatures ranging from 76° to 100°, with overnight lows between 48° and 59°. The average high for September is 85° 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 Petaluma. See also: October | November | December.
