S
M
T
W
T
F
S
30
84°
64°
31
84°
67°
1
83°
67°
2
83°
66°
3
82°
58°
4
76°
57°
5
75°
61°
6
78°
66°
7
82°
66°
8
82°
65°
9
77°
59°
10
78°
65°
11
81°
64°
12
81°
66°
13
80°
65°
14
81°
65°
15
81°
63°
16
80°
62°
17
75°
59°
18
79°
55°
19
71°
53°
20
71°
52°
21
68°
51°
22
69°
60°
23
71°
57°
24
72°
52°
25
69°
55°
26
72°
59°
27
74°
60°
28
76°
59°
29
75°
57°
30
74°
56°
1
68°
57°
2
73°
54°
3
67°
51°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Grand River
Grand River's September 2026 forecast shows daily high temperatures ranging from 67° to 84°, with overnight lows between 51° and 67°. The average high for September is 76° with an average low of 60°. 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 Grand River. See also: October | November | December.