Mammoth Cave · September
Mammoth Cave in September
September is a good time to visit Mammoth Cave — quieter than August, about as busy as October.
Expect moderate crowds (6/10), highs near 82°F, about 12.4 hours of daylight, and 3 seasonal closures in effect.
Crowd score
How busy it gets
A comfortable middle ground: some company on popular trails, but no gridlock.
About 56% of this park's busiest month.
Source: NPS Visitor Use Statistics, 2023–2025
Data: NPS visitation 2023–2025 · crowd scores computed Oct 2026 · alerts checked Oct 18, 2026. How this is calculated →
Computed from federal data · Methodology by Sharon Ben-Moshe
Visitation
Typical September visits vs. the year
September draws about 8% of Mammoth Cave’s yearly visitors.
Typical monthly recreation visits, averaged over the most recent three full years.
Source: NPS Visitor Use Statistics, 2023–2025
Weather
September weather
- Avg high
- 82°F
- Avg low
- 59°F
- Precipitation
- 3.6"
- Sunrise
- 5:26 AM
- Sunset
- 5:51 PM
- Daylight
- 12.4h
Source: NOAA 1991–2020 climate normals, BARREN RVR LAKE, KY US
What's open
Mammoth Cave in September: access
Mammoth Cave National Park is open 24-hours a day, although services such as cave tours and the visitor center are limited after-hours. There is no gate at the park entrance. Please note that camping is only possible either in designated campgrounds or backcountry campsites with a valid reservation or permit.
Seasonal closures may apply:
- Information
Temporary Closure of Select Trails for Rehabilitation Project
The Old Guides Trail, Heritage Trail, Sunset Point Trail and areas of the Sinkhole Trail are currently closed due to a trail rehabilitation project.
- Park Closure
Elevator for Accessible Tour Out of Service
Due to mechanical issues with the cave elevator, the Accessible Tour is currently unavailable. Please check back for updates or call the visitor center at (270) 758-2180.
- Park Closure
Green River Ferry Temporarily Out of Service
The Green River Ferry has temporarily suspended operation due to low water levels. Ferry service will resume once water levels rise and conditions are safe. A river forecast is available at: water.noaa.gov/gauges/03309000
Source: NPS Data API
Conditions
Current alerts
- Information
Tickets are required to enter Mammoth Cave
Reservations are strongly recommended. Reservations are the only way to ensure a spot is available for your party. Please plan accordingly by visiting Recreation.gov to secure your tickets in advance. Availability of walk-up tickets is not guaranteed.
Details on nps.gov →
Source: NPS Data API
Context
Mammoth Cave crowds across the year
Alternatives
Quieter nearby in September
FAQ
Mammoth Cave in September
How busy is Mammoth Cave in September?
September rates 6/10 for crowds (Moderate) at Mammoth Cave National Park — about 56% of its busiest month. Typical recreation visits: 56,274.
What is the weather like at Mammoth Cave in September?
In September, Mammoth Cave averages a high of 82°F and a low of 59°F, with about 3.6 inches of precipitation.
How much does it cost to visit Mammoth Cave?
Entry to Mammoth Cave is free.
When is Mammoth Cave least crowded?
Mammoth Cave is quietest in January and February. If your dates are flexible, those months bring the thinnest crowds of the year.
How many hours of daylight does Mammoth Cave get in September?
In mid-September, Mammoth Cave gets about 12.4 hours of daylight, with sunrise around 5:26 AM and sunset around 5:51 PM.