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
82°
70°
12
81°
71°
13
89°
74°
14
81°
65°
15
78°
58°
16
83°
64°
17
87°
70°
18
88°
73°
19
81°
67°
20
84°
73°
21
74°
65°
22
65°
59°
23
66°
56°
24
67°
53°
25
76°
54°
26
66°
59°
27
66°
60°
28
70°
61°
29
77°
57°
30
81°
63°
1
83°
64°
2
86°
63°
3
77°
63°
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 66° to 86°, with overnight lows between 57° and 64°. The average high for September is 76° with an average low of 61°. 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.
