Weather on September 20 at Indiana Dunes
Indiana Dunes National Park
Based on 55 years of data from Gary, IN
Planning Your Visit
September 20th in Indiana Dunes National Park (via Gary, IN) typically brings pleasant fall weather, with average highs around 75°F and lows near 55°F. Over 55 years of records, the warmest September 20th was in 2025 (80°F average), while the coldest was 1991 (51°F) — a 29°F range across recorded history. Rain or other precipitation has occurred on about 35% of September 20th dates historically, with the wettest September 20th recording 3.4" of rain. The last decade has been 5.2°F warmer on this date compared to 20-30 years ago.
The last decade has been 5.2°F warmer on this date compared to 20-30 years ago.
Planning for September 20th in Indiana Dunes? Great weather for outdoor activities. Consider bringing rain gear or an umbrella.
Year by Year History
| Year | High | Low | Precip | Snow |
|---|---|---|---|---|
| 2025 | 92°F | 69°F | 0" | 0" |
| 2024 | 87°F | 63°F | 0" | 0" |
| 2023 | 62°F | 56°F | 0.51" | 0" |
| 2022 | 73°F | 55°F | 0" | 0" |
| 2021 | 79°F | 69°F | -- | -- |
| 2020 | 74°F | 45°F | -- | -- |
| 2019 | 83°F | 63°F | 0" | 0" |
| 2018 | 77°F | 64°F | 0.03" | -- |
| 2017 | 77°F | 62°F | 0" | 0" |
| 2016 | 86°F | 63°F | 0" | 0" |
| 2015 | 68°F | 48°F | 0" | 0" |
| 2014 | 73°F | 53°F | 0" | 0" |
| 2013 | 76°F | 66°F | 0.89" | 0" |
| 2012 | 70°F | 48°F | 0" | 0" |
| 2011 | 67°F | 49°F | 0.03" | 0" |
| 2010 | 68°F | 59°F | 0" | 0" |
| 2009 | 75°F | 53°F | 0" | 0" |
| 2008 | 78°F | 55°F | 0" | 0" |
| 2007 | 82°F | 59°F | 0" | 0" |
| 2006 | 57°F | 50°F | 0" | 0" |
| 2005 | 87°F | 60°F | 0.33" | 0" |
| 2004 | 76°F | 47°F | 0" | 0" |
| 2003 | 66°F | 43°F | 0" | 0" |
| 2002 | 81°F | 69°F | 3.4" | 0" |
| 2001 | 66°F | 54°F | 0.18" | 0" |
| 2000 | 89°F | 62°F | 0.1" | 0" |
| 1999 | 65°F | 52°F | 0" | 0" |
| 1998 | 89°F | 58°F | -- | 0" |
| 1997 | 67°F | 48°F | 0" | 0" |
| 1996 | 69°F | 49°F | 0" | 0" |
| 1995 | 58°F | 49°F | 1.07" | 0" |
| 1994 | 81°F | 54°F | 0" | 0" |
| 1993 | 70°F | 54°F | 0.18" | 0" |
| 1992 | 66°F | 44°F | 0.05" | 0" |
| 1991 | 54°F | 48°F | 0" | 0" |
| 1990 | 72°F | 49°F | 0.03" | 0" |
| 1989 | 78°F | 50°F | 0" | 0" |
| 1988 | 75°F | 57°F | 0.58" | 0" |
| 1987 | 73°F | 48°F | 0.15" | 0" |
| 1986 | 70°F | 53°F | 0.74" | 0" |
| 1985 | 85°F | 61°F | 0" | 0" |
| 1984 | 87°F | 64°F | 0" | 0" |
| 1983 | 86°F | 53°F | 2.97" | 0" |
| 1982 | 70°F | 48°F | 0" | 0" |
| 1981 | 75°F | 47°F | 0" | 0" |
| 1980 | 88°F | 64°F | 0" | 0" |
| 1979 | 77°F | 38°F | 0" | 0" |
| 1978 | 91°F | 64°F | 0" | 0" |
| 1977 | 70°F | 54°F | 0" | 0" |
| 1976 | 83°F | 57°F | 0.71" | 0" |
| 1975 | 62°F | 48°F | 0" | 0" |
| 1974 | 84°F | 56°F | 0" | 0" |
| 1973 | 68°F | 54°F | 0.03" | 0" |
| 1972 | 80°F | 57°F | 0" | 0" |
| 1971 | 65°F | 50°F | 1.14" | 0" |