S
M
T
W
T
F
S
30
92°
72°
31
95°
70°
1
98°
71°
2
97°
71°
3
97°
72°
4
95°
71°
5
97°
71°
6
92°
70°
7
86°
68°
8
88°
69°
9
89°
68°
10
94°
67°
11
91°
70°
12
92°
69°
13
91°
68°
14
91°
67°
15
89°
63°
16
83°
67°
17
80°
66°
18
78°
66°
19
79°
66°
20
80°
65°
21
82°
66°
22
81°
66°
23
83°
65°
24
82°
65°
25
78°
64°
26
81°
65°
27
82°
61°
28
80°
56°
29
75°
54°
30
75°
54°
1
76°
57°
2
75°
61°
3
73°
60°
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 73° to 97°, with overnight lows between 54° and 72°. The average high for September is 85° with an average low of 65°. 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.
