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°
34°
12
66°
36°
13
64°
29°
14
53°
28°
15
62°
29°
16
65°
33°
17
63°
32°
18
62°
32°
19
64°
35°
20
62°
35°
21
59°
34°
22
56°
32°
23
56°
34°
24
57°
37°
25
47°
27°
26
48°
27°
27
57°
31°
28
52°
25°
29
49°
27°
30
46°
22°
1
51°
29°
2
54°
30°
3
55°
30°
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 46° to 66°, with overnight lows between 22° and 37°. The average high for September is 57° with an average low of 31°. 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.
