S
M
T
W
T
F
S
30
75°
53°
31
75°
52°
1
76°
51°
2
74°
50°
3
75°
50°
4
75°
51°
5
76°
55°
6
73°
52°
7
73°
53°
8
74°
55°
9
74°
48°
10
73°
47°
11
74°
49°
12
76°
52°
13
74°
47°
14
71°
53°
15
77°
55°
16
79°
55°
17
77°
54°
18
78°
44°
19
73°
44°
20
69°
45°
21
68°
46°
22
70°
51°
23
75°
51°
24
74°
50°
25
73°
41°
26
71°
40°
27
64°
40°
28
63°
41°
29
64°
41°
30
65°
47°
1
64°
46°
2
Hist. Avg.
65°
41°
3
Hist. Avg.
65°
41°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Yellowstone
Yellowstone's September 2026 forecast shows daily high temperatures ranging from 63° to 79°, with overnight lows between 40° and 55°. The average high for September is 72° with an average low of 49°. 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. See also: October | November | December.
