S
M
T
W
T
F
S
30
60°
33°
31
69°
28°
1
62°
41°
2
64°
39°
3
62°
36°
4
69°
35°
5
71°
39°
6
72°
35°
7
54°
31°
8
59°
27°
9
64°
27°
10
67°
29°
11
65°
39°
12
67°
36°
13
66°
29°
14
53°
28°
15
62°
29°
16
64°
30°
17
63°
35°
18
65°
32°
19
66°
33°
20
67°
34°
21
59°
36°
22
61°
32°
23
59°
34°
24
60°
37°
25
64°
31°
26
48°
27°
27
57°
31°
28
46°
24°
29
45°
21°
30
47°
26°
1
46°
23°
2
54°
25°
3
45°
20°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Yellowstone Lake
Yellowstone Lake's September 2026 forecast shows daily high temperatures ranging from 45° to 67°, with overnight lows between 20° and 37°. The average high for September is 57° with an average low of 30°. 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 Yellowstone Lake. See also: October | November | December.
