S
M
T
W
T
F
S
30
84°
60°
31
85°
66°
1
86°
68°
2
92°
70°
3
88°
68°
4
84°
68°
5
79°
57°
6
80°
56°
7
81°
58°
8
82°
64°
9
84°
69°
10
82°
57°
11
78°
56°
12
79°
59°
13
77°
57°
14
80°
59°
15
77°
57°
16
80°
53°
17
75°
54°
18
73°
53°
19
78°
56°
20
79°
58°
21
78°
57°
22
77°
56°
23
76°
52°
24
72°
52°
25
76°
55°
26
77°
55°
27
75°
49°
28
66°
47°
29
65°
46°
30
65°
46°
1
64°
45°
2
69°
52°
3
70°
50°
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 64° to 88°, with overnight lows between 45° and 69°. The average high for September is 76° with an average low of 56°. 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.
