S
M
T
W
T
F
S
30
90°
64°
31
93°
69°
1
93°
67°
2
92°
66°
3
93°
68°
4
93°
70°
5
92°
69°
6
92°
69°
7
91°
68°
8
88°
69°
9
87°
68°
10
90°
68°
11
89°
67°
12
90°
67°
13
90°
66°
14
88°
66°
15
89°
65°
16
85°
64°
17
83°
62°
18
84°
64°
19
87°
61°
20
80°
62°
21
80°
63°
22
80°
63°
23
82°
62°
24
86°
63°
25
86°
62°
26
87°
62°
27
86°
61°
28
85°
60°
29
84°
59°
30
84°
59°
1
82°
57°
2
85°
60°
3
85°
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 80° to 93°, with overnight lows between 57° and 70°. The average high for September is 87° 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.
