S
M
T
W
T
F
S
30
89°
72°
31
87°
73°
1
95°
74°
2
94°
75°
3
99°
76°
4
93°
70°
5
86°
66°
6
84°
65°
7
85°
64°
8
84°
63°
9
81°
65°
10
83°
66°
11
87°
66°
12
85°
64°
13
85°
63°
14
84°
62°
15
80°
66°
16
78°
66°
17
77°
61°
18
76°
57°
19
75°
58°
20
76°
60°
21
79°
61°
22
82°
63°
23
83°
65°
24
83°
63°
25
81°
62°
26
80°
62°
27
81°
63°
28
80°
62°
29
82°
61°
30
76°
59°
1
72°
56°
2
74°
59°
3
77°
59°
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 72° to 99°, with overnight lows between 56° and 76°. The average high for September is 82° 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.
