S
M
T
W
T
F
S
30
79°
48°
31
88°
45°
1
86°
56°
2
77°
56°
3
68°
48°
4
76°
42°
5
74°
51°
6
71°
53°
7
78°
54°
8
81°
44°
9
86°
44°
10
90°
46°
11
73°
50°
12
69°
51°
13
57°
45°
14
70°
44°
15
68°
44°
16
74°
48°
17
78°
53°
18
80°
54°
19
79°
53°
20
78°
52°
21
78°
51°
22
76°
51°
23
75°
50°
24
74°
52°
25
74°
46°
26
68°
51°
27
67°
46°
28
65°
42°
29
65°
44°
30
66°
47°
1
65°
44°
2
70°
45°
3
63°
41°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Heppner
Heppner's September 2026 forecast shows daily high temperatures ranging from 57° to 80°, with overnight lows between 41° and 54°. The average high for September is 71° with an average low of 48°. 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 Heppner. See also: October | November | December.