S
M
T
W
T
F
S
30
87°
63°
31
81°
63°
1
82°
62°
2
84°
63°
3
84°
63°
4
83°
62°
5
84°
62°
6
83°
61°
7
85°
51°
8
75°
51°
9
75°
53°
10
80°
52°
11
78°
51°
12
79°
50°
13
76°
55°
14
81°
58°
15
85°
59°
16
84°
58°
17
84°
61°
18
85°
59°
19
83°
59°
20
82°
62°
21
86°
57°
22
81°
53°
23
79°
55°
24
73°
48°
25
72°
50°
26
74°
49°
27
79°
49°
28
72°
53°
29
71°
54°
30
78°
48°
1
71°
55°
2
77°
53°
3
79°
53°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Walla Walla
Walla Walla's September 2026 forecast shows daily high temperatures ranging from 71° to 87°, with overnight lows between 48° and 63°. The average high for September is 80° with an average low of 56°. 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 Walla Walla. See also: October | November | December.