Isle Royale · September
Isle Royale in September
September is a good time to visit Isle Royale — quieter than August, busier than October.
Expect moderate crowds (4/10), highs near 65°F, about 12.6 hours of daylight, and 1 seasonal closure in effect.
Crowd score
How busy it gets
A comfortable middle ground: some company on popular trails, but no gridlock.
About 39% 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 12% of Isle Royale’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
- 65°F
- Avg low
- 44°F
- Precipitation
- 3.1"
- Sunrise
- 5:32 AM
- Sunset
- 6:06 PM
- Daylight
- 12.6h
Source: NOAA 1991–2020 climate normals, GRAND PORTAGE, MN US
What's open
Isle Royale in September: access
Isle Royale National Park is open annually from April 16 to October 31. Transportation services are offered from May to September. The island and its surrounding islands are closed to all visitors from November 1 to April 15 due to extreme winter weather conditions and for the safety and protection of visitors. This closure extends 4.5 miles out into Lake Superior from the island. Park headquarters during the winter is in Houghton, Michigan. Summer headquarters is located at Mott Island on Isle Royale.
Seasonal closures may apply:
- Park Closure
Tent Camping Closed at Multiple East End Campgrounds
Due to increased human-wildlife interactions and food storage concerns, individual tent sites and group sites at Three Mile, Daisy Farm, Moskey Basin, and Caribou Island Campgrounds are currently closed. Tent and hammock camping are not permitted anywhere within the campground. Off-trail camping zones 10, 11, 12, 13, 30, 31, 32, 33, 34, 35, 36, 37, 38 are closed. Shelters remain open. Closed areas will be patrolled to ensure compliance.
Details on nps.gov →
Source: NPS Data API
Conditions
Current alerts
- Information
Food Storage Regulations in Effect
Proper food storage is required on Isle Royale. All food, trash, scented items, cooking supplies, cooking utensils, and fish/fish parts must be stored properly. To learn more about food storage and to learn how to properly store your food, trash, and scented items, click "more."
Details on nps.gov → - Information
All Backpacks Must be in Storage Area at Three Mile and Rock Harbor.
All backpacks must be stored in backpack storage areas at Three Mile and Rock Harbor campgrounds. All food and scented items are to be in the Food Storage Lockers. Containers should be kept in the Food Storage Locker when space allows or near the Food Storage Locker, do not store in tents.
Details on nps.gov → - Caution
Harmful Algal Blooms Occurring in Lake Richie and Intermediate Lake
Blooms are tested for toxin levels and monitored. Toxin levels are consistently low on Isle Royale. It is not recommended to filter water in any areas where there is surface scum, strong odors, or other evidence of a significant bloom. Blooms move around depending on wind and rain – filter water from places where blooms are not present or a different water source. It is low risk to filter water from relatively clear areas of an impacted water source.
Details on nps.gov → - Caution
Island Mine Campground Stream Low
The stream has very little water flow. Campers should bring enough water to Island Mine or plan on collecting water along your route.
- Information
Boat Fuel Unavailable
Fuel for boaters will not be available from September 13 through October 31 except for emergencies only. Boaters are encouraged to bring extra fuel in containers.
Details on nps.gov →
Source: NPS Data API
Context
Isle Royale crowds across the year
FAQ
Isle Royale in September
How busy is Isle Royale in September?
September rates 4/10 for crowds (Moderate) at Isle Royale National Park — about 39% of its busiest month. Typical recreation visits: 3,475.
What is the weather like at Isle Royale in September?
In September, Isle Royale averages a high of 65°F and a low of 44°F, with about 3.1 inches of precipitation.
How much does it cost to visit Isle Royale?
Entrance to Isle Royale costs $7 ($7 per person per day to enter or remain in Isle Royale National Park. Children 15 and younger are exempt. Visiting Park Headquarters in Houghton, MI does not require a fee.).
When is Isle Royale least crowded?
Isle Royale 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 Isle Royale get in September?
In mid-September, Isle Royale gets about 12.6 hours of daylight, with sunrise around 5:32 AM and sunset around 6:06 PM.