S
M
T
W
T
F
S
30
78°
56°
31
77°
55°
1
76°
56°
2
77°
59°
3
77°
56°
4
78°
55°
5
78°
53°
6
77°
55°
7
75°
51°
8
76°
52°
9
75°
59°
10
75°
53°
11
74°
51°
12
74°
51°
13
75°
54°
14
77°
55°
15
79°
57°
16
80°
57°
17
80°
56°
18
79°
55°
19
78°
55°
20
78°
48°
21
71°
51°
22
71°
54°
23
74°
53°
24
75°
54°
25
76°
51°
26
75°
45°
27
70°
47°
28
67°
46°
29
66°
46°
30
66°
44°
1
Hist. Avg.
70°
48°
2
Hist. Avg.
70°
47°
3
Hist. Avg.
69°
47°
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 66° to 80°, with overnight lows between 44° and 59°. The average high for September is 75° with an average low of 53°. 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.
