S
M
T
W
T
F
S
30
87°
66°
31
87°
66°
1
88°
65°
2
88°
66°
3
87°
65°
4
87°
64°
5
86°
66°
6
88°
66°
7
88°
65°
8
87°
65°
9
87°
64°
10
86°
64°
11
86°
65°
12
88°
65°
13
87°
64°
14
76°
53°
15
74°
60°
16
75°
61°
17
78°
54°
18
84°
60°
19
84°
60°
20
85°
54°
21
80°
51°
22
71°
54°
23
70°
57°
24
71°
54°
25
72°
56°
26
77°
58°
27
80°
58°
28
82°
57°
29
82°
57°
30
81°
48°
1
80°
44°
2
69°
43°
3
67°
45°
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 67° to 88°, with overnight lows between 43° and 66°. The average high for September is 81° with an average low of 59°. 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.
