S
M
T
W
T
F
S
30
91°
56°
31
90°
57°
1
91°
56°
2
89°
56°
3
89°
54°
4
86°
53°
5
84°
50°
6
82°
49°
7
85°
53°
8
87°
55°
9
89°
53°
10
87°
45°
11
78°
53°
12
85°
53°
13
86°
54°
14
87°
55°
15
88°
52°
16
86°
43°
17
75°
47°
18
83°
48°
19
85°
53°
20
Hist. Avg.
80°
47°
21
Hist. Avg.
79°
46°
22
Hist. Avg.
79°
46°
23
Hist. Avg.
78°
46°
24
Hist. Avg.
78°
46°
25
Hist. Avg.
78°
45°
26
Hist. Avg.
77°
45°
27
Hist. Avg.
77°
45°
28
Hist. Avg.
76°
44°
29
Hist. Avg.
76°
44°
30
Hist. Avg.
75°
44°
1
Hist. Avg.
75°
43°
2
Hist. Avg.
74°
43°
3
Hist. Avg.
74°
43°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
*Temporarily Unavailable
September Weather in Hermiston
Hermiston's September 2026 forecast shows daily high temperatures ranging from 75° to 91°, with overnight lows between 43° and 57°. The average high for September is 86° with an average low of 52°. 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 Hermiston. See also: October | November | December.
