S
M
T
W
T
F
S
30
99°
73°
31
98°
75°
1
98°
74°
2
95°
74°
3
96°
73°
4
97°
74°
5
100°
75°
6
N/A
7
102°
71°
8
102°
73°
9
98°
73°
10
99°
72°
11
93°
73°
12
95°
72°
13
96°
71°
14
92°
70°
15
91°
68°
16
91°
68°
17
90°
69°
18
93°
68°
19
91°
66°
20
85°
61°
21
90°
68°
22
89°
67°
23
90°
67°
24
89°
66°
25
89°
66°
26
88°
65°
27
88°
65°
28
87°
64°
29
86°
65°
30
86°
62°
1
81°
55°
2
75°
53°
3
75°
52°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
*Temporarily Unavailable
September Weather in Washington
Washington's September 2026 forecast shows daily high temperatures ranging from 75° to 102°, with overnight lows between 52° and 73°. The average high for September is 90° with an average low of 66°. 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.
