S
M
T
W
T
F
S
30
94°
67°
31
94°
69°
1
99°
72°
2
100°
73°
3
99°
74°
4
100°
74°
5
95°
69°
6
91°
68°
7
88°
69°
8
88°
70°
9
90°
72°
10
91°
69°
11
89°
67°
12
85°
64°
13
86°
67°
14
84°
63°
15
80°
59°
16
76°
64°
17
79°
63°
18
75°
64°
19
74°
64°
20
75°
63°
21
77°
63°
22
82°
62°
23
78°
61°
24
75°
61°
25
80°
62°
26
78°
56°
27
72°
53°
28
70°
51°
29
69°
50°
30
71°
50°
1
70°
52°
2
72°
58°
3
73°
57°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Mammoth Cave
Mammoth Cave's September 2026 forecast shows daily high temperatures ranging from 69° to 100°, with overnight lows between 50° and 74°. The average high for September is 82° with an average low of 63°. 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 Mammoth Cave. See also: October | November | December.
