S
M
T
W
T
F
S
30
72°
31°
31
72°
27°
1
61°
25°
2
58°
27°
3
60°
29°
4
65°
36°
5
69°
36°
6
66°
31°
7
67°
25°
8
57°
27°
9
57°
26°
10
58°
32°
11
59°
27°
12
58°
25°
13
56°
34°
14
61°
38°
15
68°
29°
16
63°
24°
17
54°
25°
18
56°
27°
19
63°
25°
20
62°
28°
21
59°
35°
22
62°
34°
23
55°
29°
24
52°
29°
25
54°
34°
26
61°
30°
27
59°
36°
28
57°
34°
29
59°
34°
30
54°
26°
1
48°
22°
2
45°
22°
3
49°
26°
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 72°, with overnight lows between 22° and 38°. The average high for September is 59° with an average low of 29°. 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.
