S
M
T
W
T
F
S
30
77°
57°
31
78°
56°
1
78°
57°
2
79°
57°
3
77°
50°
4
76°
49°
5
69°
54°
6
70°
55°
7
72°
56°
8
75°
54°
9
76°
55°
10
75°
53°
11
74°
54°
12
75°
53°
13
74°
54°
14
74°
55°
15
75°
53°
16
74°
48°
17
71°
52°
18
69°
51°
19
72°
50°
20
68°
46°
21
66°
44°
22
63°
49°
23
64°
47°
24
67°
44°
25
62°
44°
26
63°
42°
27
62°
48°
28
68°
42°
29
67°
40°
30
60°
40°
1
61°
41°
2
61°
39°
3
59°
38°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Mount Desert
Mount Desert's September 2026 forecast shows daily high temperatures ranging from 59° to 79°, with overnight lows between 38° and 57°. The average high for September is 70° with an average low of 49°. 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 Mount Desert. See also: October | November | December.
