How Crowded Is Isle Royale National Park in September?

September runs about 1.3× Isle Royale National Park's average month, which makes it a busy month here — roughly 11% of the park's yearly visitors come in September.

In a typical September the park sees roughly 2,200 recreation visits, 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×).

On our Best Time to Visit score September rates 61/100 ("Good"), versus the top-rated May at 66/100 — best overall balance of crowds, weather and daylight.

Typical September weather, from 1991–2020 NOAA climate normals at the nearest station, averages a daytime high near 65°F and an overnight low around 44°F, with about 3.1" of precipitation.

That average of about 54°F is a comfortable range for hiking and being outdoors all day.

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.