S
M
T
W
T
F
S
30
60°
33°
31
69°
28°
1
62°
41°
2
63°
37°
3
61°
36°
4
64°
38°
5
68°
35°
6
66°
44°
7
58°
36°
8
54°
36°
9
61°
35°
10
62°
38°
11
59°
37°
12
58°
37°
13
59°
33°
14
61°
34°
15
63°
33°
16
67°
36°
17
61°
30°
18
62°
32°
19
51°
24°
20
51°
29°
21
55°
32°
22
59°
34°
23
62°
32°
24
51°
23°
25
47°
21°
26
47°
24°
27
49°
25°
28
55°
30°
29
58°
29°
30
59°
31°
1
53°
29°
2
54°
29°
3
58°
31°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Yellowstone National Park
Yellowstone National Park's September 2026 forecast shows daily high temperatures ranging from 47° to 68°, with overnight lows between 21° and 44°. The average high for September is 58° with an average low of 32°. 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 National Park. See also: October | November | December.
