How Crowded Is Apostle Islands in September?
September is a very busy month at Apostle Islands National Lakeshore, running about 1.7× the park's average month — roughly 14% of the year's visitors come in September. That puts it between the August peak and the December low. Overall our best-time score rates September as "Fair" for a visit. Typical September weather averages a high near 68°F and a low around 48°F, with about 3.7" of precipitation. You'll get about 12.3 hours of daylight to explore.
Frequently Asked Questions
September is very busy at Apostle Islands National Lakeshore (about 1.7× the average month). Our best-time score rates it "Fair". The single best month overall is May.
The busiest month is August and the quietest is December. September sits at about 1.7× the park's average, or 14% of annual visitation.
Source: National Park Service Visitor Use Statistics (1979–2025), NOAA NCEI Climate Normals 1991–2020. Updated 2026-06-20.