Weather on April 21 at Isle Royale
Isle Royale National Park
Based on 49 years of data from Houghton, MI
Planning Your Visit
April 21st in Isle Royale National Park (via Houghton, MI) typically brings chilly spring weather, with average highs around 49°F and lows near 31°F. Over 49 years of records, the warmest April 21st was in 1973 (65°F average), while the coldest was 2013 (26°F) — a 39°F range across recorded history. Rain or other precipitation has occurred on about 39% of April 21st dates historically, with the wettest April 21st recording 1.9" of rain. The last decade has been 2.5°F cooler on this date compared to 20-30 years ago.
The last decade has been 2.5°F cooler on this date compared to 20-30 years ago.
Planning for April 21st in Isle Royale? Bring layers as temperatures can vary throughout the day. Consider bringing rain gear or an umbrella.
Year by Year History
| Year | High | Low | Precip | Snow |
|---|---|---|---|---|
| 2025 | 37°F | 34°F | 1.9" | -- |
| 2023 | 46°F | 35°F | 0.03" | -- |
| 2022 | 42°F | 30°F | 0" | -- |
| 2021 | 35°F | 21°F | 0.13" | -- |
| 2020 | 32°F | 20°F | 0" | -- |
| 2019 | 53°F | 41°F | 0.64" | -- |
| 2018 | 57°F | 24°F | 0" | -- |
| 2017 | 52°F | 33°F | 0" | -- |
| 2016 | 58°F | 34°F | 0" | -- |
| 2015 | 35°F | 27°F | 0.25" | -- |
| 2014 | 58°F | 32°F | 0" | -- |
| 2013 | 42°F | 9°F | 0.33" | -- |
| 2012 | 43°F | 25°F | 0" | -- |
| 2011 | 49°F | 27°F | 0" | -- |
| 2010 | 39°F | 23°F | 0" | -- |
| 2009 | 33°F | 28°F | 0.41" | -- |
| 2008 | 62°F | 39°F | 0" | -- |
| 2007 | 75°F | 38°F | 0" | -- |
| 2006 | 58°F | 37°F | 0.36" | -- |
| 2005 | 55°F | 26°F | 0" | -- |
| 2004 | 42°F | 33°F | 0.05" | -- |
| 2003 | 37°F | 32°F | 0.08" | -- |
| 2002 | 33°F | 23°F | 0" | -- |
| 2001 | 52°F | 42°F | 1.75" | 0" |
| 2000 | 54°F | 30°F | 0" | 0" |
| 1999 | 51°F | 37°F | 0.05" | 0" |
| 1998 | 65°F | 33°F | 0" | 0" |
| 1997 | 48°F | 26°F | 0" | 0" |
| 1996 | 55°F | 33°F | 0" | 0" |
| 1995 | 45°F | 34°F | 0" | 0" |
| 1994 | 47°F | 28°F | 0" | 0" |
| 1993 | 50°F | 31°F | 0" | 0" |
| 1992 | 43°F | 35°F | 0.33" | 0" |
| 1991 | 50°F | 26°F | 0" | 0" |
| 1990 | 67°F | 31°F | 0" | 0" |
| 1989 | 54°F | 34°F | 0" | 0" |
| 1988 | 41°F | 25°F | 0" | 0" |
| 1982 | 41°F | 16°F | 0" | 0" |
| 1981 | 47°F | 24°F | 0.15" | 0" |
| 1980 | 70°F | 40°F | 0" | 0" |
| 1979 | 48°F | 36°F | 0.2" | 0" |
| 1978 | 42°F | 25°F | 0" | 0" |
| 1977 | 54°F | 40°F | 0.86" | 0" |
| 1976 | 45°F | 35°F | 0.91" | 0" |
| 1975 | 46°F | 26°F | 0" | 0" |
| 1974 | 64°F | 46°F | 1.22" | 0" |
| 1973 | 77°F | 53°F | 0.38" | 0" |
| 1972 | 39°F | 26°F | 0" | 0" |
| 1971 | 47°F | 33°F | 0" | 0" |