S
M
T
W
T
F
S
30
82°
54°
31
83°
59°
1
82°
59°
2
80°
53°
3
80°
49°
4
74°
49°
5
74°
53°
6
75°
57°
7
80°
56°
8
79°
51°
9
73°
50°
10
74°
56°
11
73°
57°
12
81°
57°
13
80°
56°
14
81°
55°
15
80°
52°
16
77°
54°
17
71°
46°
18
74°
46°
19
70°
44°
20
68°
42°
21
67°
43°
22
68°
51°
23
69°
44°
24
70°
43°
25
68°
50°
26
71°
51°
27
69°
50°
28
75°
49°
29
74°
44°
30
72°
43°
1
67°
48°
2
72°
47°
3
65°
40°
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 65° to 83°, with overnight lows between 40° and 59°. The average high for September is 74° with an average low of 50°. 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.
