S
M
T
W
T
F
S
30
80°
48°
31
86°
45°
1
85°
55°
2
79°
60°
3
72°
54°
4
76°
46°
5
76°
52°
6
72°
50°
7
79°
51°
8
81°
44°
9
87°
45°
10
90°
51°
11
78°
50°
12
77°
61°
13
66°
54°
14
74°
45°
15
75°
48°
16
79°
53°
17
83°
57°
18
81°
58°
19
82°
59°
20
82°
58°
21
81°
56°
22
82°
56°
23
80°
55°
24
77°
51°
25
70°
56°
26
70°
55°
27
71°
49°
28
68°
47°
29
68°
47°
30
67°
44°
1
71°
54°
2
73°
52°
3
77°
52°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Kennewick
Kennewick's September 2026 forecast shows daily high temperatures ranging from 66° to 83°, with overnight lows between 44° and 61°. 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 Kennewick. See also: October | November | December.
