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
83°
72°
13
89°
71°
14
82°
55°
15
81°
60°
16
85°
63°
17
87°
65°
18
85°
63°
19
82°
63°
20
74°
58°
21
76°
57°
22
74°
58°
23
76°
59°
24
78°
56°
25
78°
57°
26
73°
59°
27
81°
62°
28
80°
60°
29
80°
61°
30
76°
59°
1
73°
60°
2
77°
60°
3
79°
58°
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 89°, with overnight lows between 55° and 72°. The average high for September is 80° 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.
