- Best time to visit Isle Royale: June and September. The weather is at its most comfortable then, and crowds are lighter than at the peak.
- Busiest month: August, with about 8,931 visits in a typical recent year. That is 2.7 times as many as September.
- Quietest month: January (0 visits), when weather or closures keep most people away.
- Cold: average highs stay below 40°F in January to March, November and December.
Bar height: visitors that month, compared with the busiest month. Temperatures: average daily high and low (°F); rain and snow: monthly averages. Best marks the months we suggest.
Month by month
| Month | Crowds | Visits (typical) | High / low (°F) | Precipitation | Snow |
|---|---|---|---|---|---|
| January | Very quiet | 0 | 22° / 10° | n/a | n/a |
| February | Very quiet | 0 | 25° / 9° | n/a | n/a |
| March | Very quiet | 0 | 34° / 17° | n/a | n/a |
| April | Very quiet | 60 | 46° / 29° | n/a | n/a |
| May | Very quiet | 1,459 | 61° / 40° | n/a | n/a |
| June ★ | Busy | 5,971 | 70° / 49° | n/a | n/a |
| July | Busiest | 8,556 | 75° / 55° | n/a | n/a |
| August | Busiest | 8,931 | 74° / 54° | n/a | n/a |
| September ★ | Quiet | 3,364 | 66° / 47° | n/a | n/a |
| October | Very quiet | 255 | 52° / 36° | n/a | n/a |
| November | Very quiet | 0 | 38° / 26° | n/a | n/a |
| December | Very quiet | 0 | 28° / 16° | n/a | n/a |
Weather figures are NOAA 1991 to 2020 climate normals for the Hancock Houghton Co Airport station (1,095 feet above sea level), 5 miles from Houghton Visitor Center. Visitor numbers are the median of 2022 to 2025 monthly recreation visits from the National Park Service.
By season
- Spring (March to May): 5% of the year’s visits; average highs 34° to 61°F.
- Summer (June to August): 82% of the year’s visits; average highs 70° to 75°F.
- Fall (September to November): 13% of the year’s visits; average highs 38° to 66°F.
- Winter (December to February): 0% of the year’s visits; average highs 22° to 28°F.
Weekends and holidays
Even in a quiet month, holiday weekends fill parking lots and campgrounds. The 2027 federal holidays to plan around:
- Martin Luther King Jr. Day: Monday, January 18
- Presidents Day: Monday, February 15
- Memorial Day: Monday, May 31
- Juneteenth: Saturday, June 19
- Independence Day: Sunday, July 4 (observed Monday, July 5)
- Labor Day: Monday, September 6
- Columbus Day and Indigenous Peoples Day: Monday, October 11
- Veterans Day: Thursday, November 11
- Thanksgiving: Thursday, November 25
Entrance is free for U.S. residents on the park service’s fee-free days. The last one in 2026 is Veterans Day, November 11; the 2027 dates had not been announced when we checked. Free days are often busier. See the crowd calendar for all 64 parks.
Weather, in the park service’s words
Isle Royale National Park is a remote island wilderness in the middle of Lake Superior. Weather influences traveling to and from the island, as well as your trip once you arrive. For the most up-to-date weather information, call (906) 482-0984 or email isro_parkinfo@nps.gov prior to your trip.
From the National Park Service (public domain).
Today at Isle Royale
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Alerts: National Park Service, checked hourly. Forecast: National Weather Service, for the middle of the park. Always confirm on the official park site before you set out.
Sources
- National Park Service visitor use statistics (IRMA): monthly recreation visits, 2022 to 2025
- NOAA NCEI U.S. Climate Normals, 1991 to 2020 (monthly)
- National Park Service Data API: weather overview (public domain)
Last checked 1 November 2026.