S
M
T
W
T
F
S
30
78°
65°
31
84°
69°
1
89°
71°
2
94°
70°
3
87°
67°
4
84°
64°
5
81°
60°
6
79°
57°
7
76°
56°
8
73°
57°
9
76°
56°
10
77°
54°
11
76°
52°
12
75°
52°
13
74°
54°
14
76°
51°
15
79°
57°
16
78°
56°
17
78°
55°
18
74°
55°
19
78°
56°
20
79°
56°
21
79°
55°
22
78°
56°
23
79°
55°
24
78°
54°
25
77°
54°
26
76°
52°
27
77°
53°
28
76°
52°
29
75°
51°
30
73°
50°
1
73°
50°
2
74°
51°
3
74°
50°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Grass Lake
Grass Lake's September 2026 forecast shows daily high temperatures ranging from 73° to 94°, with overnight lows between 50° and 71°. The average high for September is 78° with an average low of 56°. 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 Grass Lake. See also: October | November | December.
