S
M
T
W
T
F
S
30
74°
48°
31
80°
46°
1
71°
55°
2
64°
48°
3
65°
48°
4
68°
48°
5
72°
46°
6
75°
50°
7
72°
51°
8
71°
50°
9
76°
52°
10
77°
52°
11
74°
51°
12
73°
51°
13
72°
49°
14
76°
47°
15
73°
47°
16
67°
46°
17
66°
47°
18
66°
43°
19
67°
48°
20
65°
44°
21
65°
41°
22
66°
42°
23
63°
41°
24
63°
40°
25
64°
40°
26
68°
41°
27
69°
48°
28
63°
46°
29
64°
41°
30
70°
47°
1
65°
47°
2
61°
45°
3
63°
42°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Washington State Capitol
Washington State Capitol's September 2026 forecast shows daily high temperatures ranging from 61° to 77°, with overnight lows between 40° and 55°. The average high for September is 68° with an average low of 46°. 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 State Capitol. See also: October | November | December.
