S
M
T
W
T
F
S
30
89°
66°
31
88°
66°
1
89°
67°
2
88°
66°
3
88°
64°
4
84°
63°
5
84°
64°
6
88°
67°
7
88°
67°
8
87°
66°
9
87°
67°
10
86°
67°
11
88°
66°
12
87°
67°
13
87°
66°
14
86°
65°
15
86°
62°
16
85°
64°
17
86°
62°
18
84°
60°
19
85°
63°
20
83°
64°
21
84°
64°
22
83°
63°
23
83°
62°
24
84°
63°
25
83°
62°
26
79°
60°
27
Hist. Avg.
80°
58°
28
Hist. Avg.
80°
57°
29
Hist. Avg.
79°
57°
30
Hist. Avg.
79°
56°
1
Hist. Avg.
79°
56°
2
Hist. Avg.
78°
56°
3
Hist. Avg.
78°
55°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
*Temporarily Unavailable
September Weather in Washington
Washington's September 2026 forecast shows daily high temperatures ranging from 79° to 89°, with overnight lows between 60° and 67°. The average high for September is 86° with an average low of 64°. 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.
