S
M
T
W
T
F
S
30
86°
63°
31
86°
63°
1
85°
62°
2
86°
63°
3
86°
62°
4
85°
62°
5
85°
61°
6
86°
63°
7
87°
62°
8
84°
61°
9
77°
60°
10
81°
59°
11
84°
60°
12
84°
60°
13
85°
58°
14
71°
47°
15
72°
56°
16
72°
54°
17
74°
52°
18
83°
58°
19
84°
48°
20
82°
45°
21
71°
46°
22
70°
47°
23
67°
53°
24
71°
49°
25
76°
53°
26
78°
54°
27
77°
55°
28
80°
54°
29
80°
52°
30
78°
41°
1
76°
39°
2
62°
39°
3
64°
45°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Washington
Washington's September 2026 forecast shows daily high temperatures ranging from 62° to 87°, with overnight lows between 39° and 63°. The average high for September is 79° 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 Washington. See also: October | November | December.
