S
M
T
W
T
F
S
30
80°
53°
31
79°
55°
1
81°
55°
2
80°
54°
3
81°
54°
4
79°
54°
5
80°
50°
6
81°
49°
7
79°
54°
8
78°
55°
9
76°
54°
10
70°
48°
11
69°
45°
12
68°
45°
13
69°
46°
14
72°
51°
15
68°
42°
16
67°
43°
17
68°
53°
18
68°
52°
19
69°
54°
20
76°
48°
21
69°
43°
22
65°
43°
23
66°
45°
24
67°
48°
25
69°
52°
26
74°
52°
27
73°
53°
28
74°
51°
29
73°
41°
30
64°
45°
1
68°
47°
2
68°
42°
3
61°
40°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Chehalis
Chehalis's September 2026 forecast shows daily high temperatures ranging from 61° to 81°, with overnight lows between 40° and 55°. The average high for September is 72° with an average low of 49°. 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 Chehalis. See also: October | November | December.
