S
M
T
W
T
F
S
30
87°
54°
31
86°
45°
1
74°
44°
2
73°
47°
3
82°
49°
4
83°
54°
5
84°
46°
6
79°
43°
7
70°
41°
8
69°
45°
9
67°
42°
10
68°
48°
11
71°
39°
12
68°
41°
13
69°
50°
14
77°
47°
15
76°
41°
16
66°
39°
17
65°
40°
18
67°
41°
19
72°
39°
20
73°
45°
21
72°
43°
22
71°
38°
23
63°
41°
24
64°
45°
25
70°
43°
26
64°
38°
27
61°
45°
28
68°
40°
29
61°
42°
30
65°
40°
1
59°
36°
2
59°
36°
3
65°
40°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Grangeville
Grangeville's September 2026 forecast shows daily high temperatures ranging from 59° to 87°, with overnight lows between 36° and 54°. The average high for September is 71° with an average low of 43°. 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 Grangeville. See also: October | November | December.