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
83°
55°
15
80°
57°
16
85°
65°
17
87°
68°
18
88°
67°
19
83°
67°
20
83°
66°
21
76°
60°
22
74°
61°
23
74°
59°
24
75°
58°
25
77°
58°
26
76°
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 88°, with overnight lows between 55° and 68°. The average high for September is 79° 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.
