S
M
T
W
T
F
S
30
82°
58°
31
83°
59°
1
79°
55°
2
78°
53°
3
78°
54°
4
83°
58°
5
81°
56°
6
76°
48°
7
76°
52°
8
80°
53°
9
85°
56°
10
87°
58°
11
87°
58°
12
86°
57°
13
85°
57°
14
82°
51°
15
80°
50°
16
79°
52°
17
82°
53°
18
85°
57°
19
86°
54°
20
85°
54°
21
79°
53°
22
82°
57°
23
84°
54°
24
82°
53°
25
81°
56°
26
82°
56°
27
83°
53°
28
80°
51°
29
73°
50°
30
72°
52°
1
70°
48°
2
67°
44°
3
65°
47°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Prosser
Prosser's September 2026 forecast shows daily high temperatures ranging from 65° to 87°, with overnight lows between 44° and 59°. The average high for September is 80° with an average low of 54°. 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 Prosser. See also: October | November | December.
