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Isle Royale National Park in September

Busy1.3× average month · best-time score 65/100Our recommended month

September at Isle Royale National Park averages a daytime high near 65°F and an overnight low around 44°F, with about 3.1" of precipitation. Visitation runs about 1.3× the park's average month, which makes September a busy month here.

Average low
44°F
Average high
65°F

Range across the year: 1°F to 74°F

Crowds
1.3× averageBusy
  1. J
  2. F
  3. M
  4. A
  5. M
  6. J
  7. J
  8. A
  9. S
  10. O
  11. N
  12. D
Precipitation
3.1 in
Daylight
12.3 hours

Roughly 11% of the park's yearly visitors come in September: roughly 2,200 recreation visits in a typical year, based on National Park Service monthly counts from 1979 to 2025.

That makes September the 4th-busiest of the park's twelve months, sitting between the August peak (4.2×) and the January low (0×).

September is our recommended month at Isle Royale: the lightest crowds of the park's good-weather months.

The daily average of about 54°F is a comfortable range for hiking and being outdoors all day. These figures are 1991–2020 NOAA climate normals from the nearest station, about 40 miles from the park.

Because June, July and August together draw about 83% of annual visitors, choosing September instead steps outside that summer crush — the single biggest lever on how crowded the park feels.

You'll have about 12.3 hours of daylight in September to explore — between the 8.2-hour midwinter low and the 15.8-hour summer high.

Park-wide, 2019 drew 26,410 recreation visits, up 2.4% from 25,798 in 2018.

Across the past decade overall visitation has risen about 56.7%, so a September visit is likely to feel busier than it did a few years ago.

How September compares with the months around it

MonthAvg high / lowCrowdsBest-time score
August73°F / 52°F4.2× Very busy46 Fair
September65°F / 44°F1.3× Busy65 Good
October51°F / 33°F0.1× Very quiet16 Poor

All twelve months at Isle Royale, with the best time to visit.

Things to do at Isle Royale in September

The National Park Service tags 40 Isle Royale activities for fall. Here are 8 of them. Each links to the park's own page for it.

Reviewed by WhenToVisitParks Editorial Team · Updated

Frequently Asked Questions

September averages a daytime high near 65°F and an overnight low around 44°F at Isle Royale National Park, with about 3.1 inches of precipitation. These are 1991–2020 NOAA climate normals from the nearest station, about 40 miles from the park, so conditions inside the park can differ, especially at other elevations.

September is busy at Isle Royale National Park (about 1.3× the average month). Our best-time score rates it "Good" at 65/100. September is our recommended month for this park.

The busiest month is August and the quietest is January. September sits at about 1.3× the park's average, or 11% of annual visitation.

A typical September sees about 2,000 recreation visits at Isle Royale National Park, based on National Park Service monthly counts from 1979–2025.

Where to stay near Isle Royale in September

Booking a September trip to Isle Royale National Park? Compare hotels, cabins and vacation rentals near the park with live September availability and prices.

Top-rated places to stay near Isle Royale

Prices for Oct 30–Nov 1, 4 adults. Change dates on the map below.

Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.

Visiting Isle Royale in September?

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See the full ranking of the best national parks to visit in September.

Source: National Park Service Visitor Use Statistics (1979–2025), NOAA NCEI Climate Normals 1991–2020. Updated 2026-10-11.