S
M
T
W
T
F
S
30
87°
69°
31
91°
69°
1
94°
74°
2
96°
75°
3
95°
76°
4
95°
72°
5
91°
72°
6
82°
67°
7
84°
64°
8
85°
62°
9
86°
61°
10
93°
69°
11
95°
74°
12
91°
73°
13
91°
76°
14
91°
69°
15
82°
61°
16
83°
59°
17
88°
61°
18
93°
71°
19
86°
69°
20
89°
64°
21
91°
69°
22
87°
72°
23
76°
67°
24
68°
57°
25
68°
53°
26
75°
52°
27
78°
55°
28
81°
58°
29
82°
62°
30
83°
65°
1
85°
66°
2
82°
64°
3
78°
64°
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 68° to 85°, with overnight lows between 52° and 66°. The average high for September is 78° with an average low of 60°. 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.
