S
M
T
W
T
F
S
30
97°
64°
31
100°
64°
1
100°
68°
2
100°
72°
3
100°
72°
4
100°
72°
5
102°
73°
6
91°
75°
7
90°
66°
8
93°
63°
9
95°
70°
10
79°
70°
11
86°
68°
12
93°
64°
13
88°
68°
14
91°
64°
15
100°
75°
16
93°
75°
17
99°
72°
18
99°
72°
19
99°
73°
20
93°
68°
21
73°
66°
22
72°
64°
23
73°
57°
24
66°
55°
25
77°
54°
26
75°
61°
27
77°
61°
28
81°
55°
29
86°
52°
30
93°
72°
1
83°
64°
2
75°
49°
3
74°
46°
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 74° to 93°, with overnight lows between 46° and 72°. The average high for September is 81° with an average low of 58°. 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.
