Weather on September 20 at Gateway Arch
Gateway Arch National Park
Based on 52 years of data from St. Louis, MO
Planning Your Visit
September 20th in Gateway Arch National Park (via St. Louis, MO) typically brings warm fall weather, with average highs around 81°F and lows near 59°F. Over 52 years of records, the warmest September 20th was in 2017 (84°F average), while the coldest was 1991 (48°F) — a 36°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 4.22" of rain. The last decade has been 6.6°F warmer on this date compared to 20-30 years ago.
The last decade has been 6.6°F warmer on this date compared to 20-30 years ago.
Planning for September 20th in Gateway Arch? Stay hydrated and seek shade during peak afternoon hours. Consider bringing rain gear or an umbrella.
Year by Year History
| Year | High | Low | Precip | Snow |
|---|---|---|---|---|
| 2025 | 89°F | 60°F | 0.03" | 0" |
| 2024 | 95°F | 67°F | 0" | 0" |
| 2023 | 77°F | 56°F | 0.46" | 0" |
| 2022 | 99°F | 67°F | 0" | 0" |
| 2021 | 86°F | 70°F | 0" | 0" |
| 2020 | 77°F | 42°F | 0" | 0" |
| 2019 | 89°F | 66°F | 0.03" | 0" |
| 2018 | 95°F | 72°F | 0" | 0" |
| 2017 | 95°F | 74°F | 0" | 0" |
| 2016 | 87°F | 69°F | 0" | 0" |
| 2015 | 75°F | 57°F | 0" | 0" |
| 2014 | 79°F | 63°F | 0" | 0" |
| 2013 | 92°F | 69°F | 1.14" | 0" |
| 2012 | 76°F | 57°F | 0" | 0" |
| 2011 | 71°F | 52°F | 0" | -- |
| 2010 | 75°F | 64°F | 1.78" | 0" |
| 2009 | 79°F | 61°F | 0.66" | 0" |
| 2008 | 81°F | 62°F | 0" | 0" |
| 2007 | 90°F | 64°F | 0" | 0" |
| 2006 | 66°F | 41°F | 0" | 0" |
| 2005 | 91°F | 67°F | 4.22" | 0" |
| 2004 | 84°F | 49°F | 0" | 0" |
| 2003 | 68°F | 47°F | 0" | 0" |
| 2002 | 81°F | 65°F | 1.57" | 0" |
| 2001 | 70°F | 53°F | 0" | 0" |
| 2000 | 92°F | 58°F | 0" | 0" |
| 1999 | 71°F | 59°F | 0.28" | 0" |
| 1998 | 87°F | 66°F | 0" | 0" |
| 1997 | 91°F | 67°F | 0" | 0" |
| 1996 | 75°F | 61°F | 0.05" | 0" |
| 1995 | 65°F | 58°F | 0" | 0" |
| 1994 | 83°F | 51°F | 0" | 0" |
| 1993 | 80°F | 61°F | 1.73" | 0" |
| 1992 | 70°F | 52°F | 0.69" | 0" |
| 1991 | 59°F | 37°F | 0" | 0" |
| 1990 | 77°F | 63°F | 0" | 0" |
| 1989 | 81°F | 54°F | 0" | 0" |
| 1988 | 81°F | 48°F | 0" | 0" |
| 1987 | 75°F | 47°F | 0" | 0" |
| 1986 | 90°F | 66°F | 0.1" | 0" |
| 1985 | 90°F | 51°F | 0" | 0" |
| 1981 | 71°F | 45°F | 0" | 0" |
| 1980 | 90°F | 58°F | 0" | 0" |
| 1979 | 82°F | 52°F | 0" | 0" |
| 1978 | 96°F | 70°F | 0" | 0" |
| 1977 | 67°F | 50°F | 0.08" | 0" |
| 1976 | 93°F | 65°F | 1.5" | 0" |
| 1975 | 67°F | 48°F | 0.1" | 0" |
| 1974 | 85°F | 65°F | 0" | 0" |
| 1973 | 69°F | 49°F | 0.15" | 0" |
| 1972 | 93°F | 73°F | 0" | 0" |
| 1971 | 69°F | -- | 2.49" | 0" |