S
M
T
W
T
F
S
30
69°
63°
31
81°
64°
1
90°
63°
2
71°
58°
3
70°
57°
4
70°
59°
5
74°
62°
6
76°
58°
7
70°
55°
8
69°
55°
9
73°
58°
10
71°
55°
11
66°
55°
12
67°
53°
13
66°
54°
14
68°
51°
15
73°
56°
16
72°
56°
17
69°
55°
18
69°
57°
19
70°
56°
20
71°
55°
21
71°
57°
22
70°
56°
23
71°
55°
24
70°
56°
25
71°
56°
26
70°
54°
27
71°
55°
28
70°
53°
29
67°
52°
30
66°
53°
1
67°
54°
2
67°
52°
3
66°
52°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Grand Marais
Grand Marais's September 2026 forecast shows daily high temperatures ranging from 66° to 90°, with overnight lows between 51° and 63°. The average high for September is 70° 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 Grand Marais. See also: October | November | December.
