Parks / Isle Royale
When to visit
Isle Royale.
The park drew an average of 25K recreation visits a year over 2016–2025. August is the busiest month at 32.6% of the year's visits, and January the quietest — 509.8× fewer people.
Crowds
August averages 8,157 recreation visits against 16 in January. Visit counts are the National Park Service's own monthly totals for the whole park, so unlike the weather figures below they describe every entrance and every trailhead at once.
Conditions through the year
July is the warmest month at 1,289 feet, averaging a daily high of 66°F, and January the coldest at 21°F with lows near 13°F. April is the wettest at 3.4 inches, January the driest at 1.6.
Daylight runs from 8h 30m in December to 16h 0m in June, a difference of 7h 30m of usable time in a day.
Snow shows up in the record in January, February, March, April, October, November and December. That is snowfall at the grid cell, not road or trail status — parks close roads on their own schedule and conditions, and the park's own alerts are the only authority on what is open.
Those temperatures come from a reanalysis grid cell centred at 1,289 feet. A park that spans a range of elevations is warmer in some places and colder in others than one cell can show, and most parks span a wide one. Read the month-to-month shape — which months run warm, wet or snowy relative to each other — rather than any single figure as the temperature you will meet at a given trailhead.
Every month
| Month | High | Low | Wet days | Snow days | Daylight | Visits |
|---|---|---|---|---|---|---|
| January | 21° | 13° | 10 | 8 | 8h 54m | 16 |
| February | 21° | 11° | 11 | 9 | 10h 18m | 25 |
| March | 30° | 21° | 7 | 5 | 11h 54m | 30 |
| April | 38° | 28° | 10 | 5 | 13h 42m | 59 |
| May | 51° | 38° | 9 | 0 | 15h 12m | 1,144 |
| June | 60° | 46° | 9 | 0 | 16h 0m | 4,722 |
| July | 66° | 54° | 7 | 0 | 15h 36m | 7,510 |
| August | 66° | 57° | 9 | 0 | 14h 12m | 8,157 |
| September | 61° | 53° | 10 | 0 | 12h 36m | 3,042 |
| October | 49° | 42° | 12 | 1 | 10h 48m | 248 |
| November | 36° | 29° | 10 | 5 | 9h 18m | 24 |
| December | 27° | 18° | 11 | 9 | 8h 30m | 25 |
Averages over 10 years, 2016–2025. Wet days count days with at least 0.04″ of precipitation; snow days at least 0.4″ of snowfall.
There is no best month here
This page does not pick one. Crowds and weather alone cannot: in the desert parks the emptiest months are empty because the heat is dangerous, and in the mountain parks the quietest ones are quiet because the roads are shut. What a month has usually been like and what it will be like on your date are also different claims — for the second, the planner reads the live seven-day forecast and the park's own notices.
ParkReady is independent and is not affiliated with the National Park Service. Road, trail and campground status comes from the park, and the park is the only authority on it.
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