S
M
T
W
T
F
S
30
91°
64°
31
93°
70°
1
97°
70°
2
96°
71°
3
97°
72°
4
98°
72°
5
98°
75°
6
87°
66°
7
86°
64°
8
91°
72°
9
97°
70°
10
76°
61°
11
84°
64°
12
87°
66°
13
88°
67°
14
85°
63°
15
84°
59°
16
83°
58°
17
85°
61°
18
83°
58°
19
81°
57°
20
79°
56°
21
83°
61°
22
76°
61°
23
79°
60°
24
83°
62°
25
84°
62°
26
84°
61°
27
83°
62°
28
83°
62°
29
84°
61°
30
83°
61°
1
83°
57°
2
81°
50°
3
69°
47°
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 69° to 97°, with overnight lows between 47° and 72°. The average high for September is 83° 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.
