Weather on August 21 at Isle Royale
Isle Royale National Park
Based on 50 years of data from Houghton, MI
Planning Your Visit
August 21st in Isle Royale National Park (via Houghton, MI) typically brings pleasant summer weather, with average highs around 74°F and lows near 55°F. Over 50 years of records, the warmest August 21st was in 1976 (79°F average), while the coldest was 2004 (52°F) — a 27°F range across recorded history. Rain or other precipitation has occurred on about 32% of August 21st dates historically, with the wettest August 21st recording 2.95" of rain. The last decade has been 1.4°F cooler on this date compared to 20-30 years ago.
The last decade has been 1.4°F cooler on this date compared to 20-30 years ago.
Planning for August 21st in Isle Royale? Great weather for outdoor activities. Consider bringing rain gear or an umbrella.
Year by Year History
| Year | High | Low | Precip | Snow |
|---|---|---|---|---|
| 2025 | 79°F | 51°F | 0" | -- |
| 2024 | 75°F | 45°F | 0" | -- |
| 2023 | 67°F | 57°F | 0.03" | -- |
| 2022 | 75°F | 50°F | 0" | -- |
| 2021 | 81°F | 63°F | 0.51" | -- |
| 2020 | 73°F | 62°F | 0" | -- |
| 2019 | 70°F | 49°F | 0" | -- |
| 2018 | 65°F | 55°F | 0" | -- |
| 2017 | 74°F | 56°F | 0.58" | -- |
| 2016 | 67°F | 54°F | 0.23" | -- |
| 2015 | 79°F | 45°F | 0" | -- |
| 2014 | 67°F | 57°F | 0" | -- |
| 2013 | 85°F | 61°F | 0" | -- |
| 2012 | 76°F | 45°F | 0" | -- |
| 2011 | 68°F | 50°F | 0.13" | -- |
| 2010 | 65°F | 59°F | 0" | -- |
| 2009 | 57°F | 51°F | 1.45" | -- |
| 2008 | 81°F | 56°F | 0" | -- |
| 2007 | 70°F | 57°F | 0.08" | -- |
| 2006 | 74°F | 55°F | 0" | -- |
| 2005 | 61°F | 54°F | 0" | -- |
| 2004 | 62°F | 42°F | 0" | -- |
| 2003 | 83°F | 70°F | 0.13" | 0" |
| 2002 | 80°F | 59°F | 2.13" | 0" |
| 2001 | 83°F | 53°F | 0" | 0" |
| 2000 | 77°F | 53°F | 0" | 0" |
| 1999 | 76°F | 56°F | 0" | 0" |
| 1998 | 77°F | 60°F | 0" | 0" |
| 1997 | 66°F | 54°F | 0.03" | 0" |
| 1996 | 78°F | 52°F | 0" | 0" |
| 1995 | 87°F | 64°F | 0" | 0" |
| 1994 | 74°F | 54°F | 0" | 0" |
| 1993 | 74°F | 46°F | 0" | 0" |
| 1992 | 69°F | 60°F | 0.03" | 0" |
| 1991 | 80°F | 53°F | 0" | 0" |
| 1990 | 74°F | 49°F | 0" | 0" |
| 1989 | 68°F | 53°F | 0" | 0" |
| 1988 | 72°F | 52°F | 0" | 0" |
| 1983 | 75°F | 59°F | 0.15" | 0" |
| 1981 | 80°F | 57°F | 0" | 0" |
| 1980 | 73°F | 61°F | 0" | 0" |
| 1979 | 73°F | 53°F | 0" | 0" |
| 1978 | 85°F | 60°F | 0" | 0" |
| 1977 | 62°F | 50°F | 0" | 0" |
| 1976 | 93°F | 64°F | 0" | 0" |
| 1975 | 67°F | 56°F | 1.73" | 0" |
| 1974 | 76°F | 68°F | 2.95" | 0" |
| 1973 | 70°F | 53°F | 0" | 0" |
| 1972 | 81°F | 52°F | 1.98" | 0" |
| 1971 | 79°F | 59°F | 0.08" | 0" |