S
M
T
W
T
F
S
30
84°
40°
31
75°
36°
1
68°
38°
2
69°
42°
3
74°
46°
4
79°
49°
5
79°
48°
6
78°
40°
7
71°
38°
8
66°
41°
9
65°
42°
10
66°
46°
11
66°
39°
12
65°
38°
13
65°
46°
14
73°
48°
15
72°
42°
16
64°
37°
17
62°
39°
18
63°
41°
19
72°
36°
20
61°
34°
21
60°
34°
22
62°
32°
23
59°
33°
24
58°
42°
25
59°
39°
26
63°
33°
27
59°
42°
28
57°
35°
29
59°
37°
30
58°
34°
1
55°
35°
2
56°
35°
3
59°
41°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Lake McDonald
Lake McDonald's September 2026 forecast shows daily high temperatures ranging from 55° to 84°, with overnight lows between 32° and 49°. The average high for September is 66° with an average low of 39°. 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 Lake McDonald. See also: October | November | December.
