S
M
T
W
T
F
S
30
89°
72°
31
87°
73°
1
98°
77°
2
91°
74°
3
91°
71°
4
90°
72°
5
85°
72°
6
85°
66°
7
84°
64°
8
86°
64°
9
89°
70°
10
91°
74°
11
81°
71°
12
80°
72°
13
85°
68°
14
84°
62°
15
81°
63°
16
87°
67°
17
87°
68°
18
88°
60°
19
78°
60°
20
78°
58°
21
76°
57°
22
77°
58°
23
80°
59°
24
81°
58°
25
75°
57°
26
73°
59°
27
81°
62°
28
82°
61°
29
77°
58°
30
80°
62°
1
79°
60°
2
77°
57°
3
77°
60°
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 73° to 88°, with overnight lows between 57° and 72°. The average high for September is 80° with an average low of 62°. 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.
