S
M
T
W
T
F
S
30
80°
62°
31
80°
61°
1
79°
60°
2
78°
57°
3
77°
57°
4
74°
59°
5
71°
51°
6
70°
58°
7
70°
59°
8
76°
59°
9
78°
60°
10
68°
54°
11
67°
55°
12
69°
55°
13
72°
60°
14
76°
59°
15
77°
54°
16
68°
50°
17
67°
54°
18
71°
53°
19
67°
51°
20
74°
60°
21
74°
56°
22
65°
52°
23
Hist. Avg.
69°
52°
24
Hist. Avg.
69°
52°
25
Hist. Avg.
69°
52°
26
Hist. Avg.
68°
52°
27
Hist. Avg.
68°
51°
28
Hist. Avg.
68°
51°
29
Hist. Avg.
67°
51°
30
Hist. Avg.
67°
51°
1
Hist. Avg.
66°
50°
2
Hist. Avg.
66°
50°
3
Hist. Avg.
65°
50°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
*Temporarily Unavailable
September Weather in Seattle
Seattle's September 2026 forecast shows daily high temperatures ranging from 65° to 80°, with overnight lows between 50° and 62°. The average high for September is 73° 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 Seattle. See also: October | November | December.
