Weather on September 18 at Isle Royale
Isle Royale National Park
Based on 50 years of data from Houghton, MI
Planning Your Visit
September 18th in Isle Royale National Park (via Houghton, MI) typically brings mild fall weather, with average highs around 66°F and lows near 48°F. Over 50 years of records, the warmest September 18th was in 2019 (73°F average), while the coldest was 2014 (42°F) — a 31°F range across recorded history. Rain or other precipitation has occurred on about 38% of September 18th dates historically, with the wettest September 18th recording 2.95" of rain. The last decade has been 5.0°F cooler on this date compared to 20-30 years ago.
The last decade has been 5.0°F cooler on this date compared to 20-30 years ago.
Planning for September 18th 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 | 66°F | 54°F | 0" | -- |
| 2024 | 84°F | 61°F | 0" | -- |
| 2023 | 62°F | 41°F | 0" | -- |
| 2022 | 73°F | 60°F | 1.22" | -- |
| 2021 | 70°F | 40°F | 0" | -- |
| 2020 | 56°F | 29°F | 0" | -- |
| 2019 | 83°F | 64°F | 0" | -- |
| 2018 | 54°F | 41°F | 0" | -- |
| 2017 | 61°F | 39°F | 0.2" | -- |
| 2016 | 73°F | 61°F | 0.15" | -- |
| 2015 | 69°F | 54°F | 0.08" | -- |
| 2014 | 51°F | 33°F | 0" | -- |
| 2013 | 66°F | 51°F | 0.03" | -- |
| 2012 | 49°F | 38°F | 0.79" | -- |
| 2011 | 61°F | 46°F | 0.51" | -- |
| 2010 | 53°F | 41°F | 0" | -- |
| 2009 | 61°F | 43°F | 0" | -- |
| 2008 | 67°F | 45°F | 0" | -- |
| 2007 | 73°F | 61°F | 2.95" | -- |
| 2006 | 58°F | 45°F | 0" | -- |
| 2005 | 70°F | 53°F | 0" | -- |
| 2004 | 72°F | 47°F | 0" | -- |
| 2003 | 80°F | 59°F | 0" | -- |
| 2002 | 75°F | 57°F | 0" | 0" |
| 2001 | 63°F | 56°F | 0" | 0" |
| 2000 | 89°F | 53°F | 0" | 0" |
| 1999 | 75°F | 47°F | 0" | 0" |
| 1998 | 80°F | 58°F | 0" | 0" |
| 1997 | 73°F | 57°F | 0.03" | 0" |
| 1996 | 66°F | 45°F | 0" | 0" |
| 1995 | 68°F | 42°F | 0" | 0" |
| 1994 | 75°F | 52°F | 0" | 0" |
| 1993 | 50°F | 35°F | 0" | 0" |
| 1992 | 56°F | 45°F | 0.28" | 0" |
| 1991 | 53°F | 41°F | 0.28" | 0" |
| 1990 | 65°F | 40°F | 0.25" | 0" |
| 1989 | 82°F | 55°F | 0" | 0" |
| 1988 | 68°F | 55°F | 0" | 0" |
| 1983 | 61°F | 53°F | 0.08" | 0" |
| 1981 | 63°F | 47°F | 0.03" | 0" |
| 1980 | 50°F | 43°F | 1.19" | 0" |
| 1979 | 62°F | 40°F | 0" | 0" |
| 1978 | 55°F | 51°F | 0.03" | 0" |
| 1977 | 66°F | 55°F | 1.17" | 0" |
| 1976 | 75°F | 51°F | 0" | 0" |
| 1975 | 71°F | 53°F | 0.56" | 0" |
| 1974 | 69°F | 37°F | 0.56" | 0" |
| 1973 | 60°F | 43°F | 0" | 0" |
| 1972 | 62°F | 46°F | 0" | 0" |
| 1971 | 56°F | 36°F | 0" | 0" |