Weather on September 21 at Gateway Arch
Gateway Arch National Park
Based on 52 years of data from St. Louis, MO
Planning Your Visit
September 21st in Gateway Arch National Park (via St. Louis, MO) typically brings pleasant fall weather, with average highs around 79°F and lows near 58°F. Over 52 years of records, the warmest September 21st was in 2017 (86°F average), while the coldest was 1995 (54°F) — a 32°F range across recorded history. Rain or other precipitation has occurred on about 35% of September 21st dates historically, with the wettest September 21st recording 4.06" of rain. The last decade has been 9.1°F warmer on this date compared to 20-30 years ago.
The last decade has been 9.1°F warmer on this date compared to 20-30 years ago.
Planning for September 21st in Gateway Arch? Great weather for outdoor activities. Consider bringing rain gear or an umbrella.
Year by Year History
| Year | High | Low | Precip | Snow |
|---|---|---|---|---|
| 2025 | 87°F | 60°F | 0.41" | 0" |
| 2024 | 94°F | 68°F | 0" | 0" |
| 2023 | 85°F | 59°F | 0" | 0" |
| 2022 | 97°F | 67°F | 4.06" | 0" |
| 2021 | 74°F | 56°F | 2.51" | 0" |
| 2020 | 79°F | 44°F | 0" | 0" |
| 2019 | 84°F | 70°F | 0" | 0" |
| 2018 | 83°F | 65°F | 0.36" | 0" |
| 2017 | 94°F | 78°F | 0" | 0" |
| 2016 | 91°F | 70°F | 0" | 0" |
| 2015 | 74°F | 54°F | 0" | 0" |
| 2014 | 80°F | 58°F | 0.03" | 0" |
| 2013 | 71°F | 54°F | 0.08" | 0" |
| 2012 | 79°F | 56°F | 0" | 0" |
| 2011 | 76°F | 56°F | 0" | -- |
| 2010 | 90°F | 64°F | 0" | 0" |
| 2009 | 69°F | 61°F | 0.51" | 0" |
| 2008 | 73°F | 61°F | 0" | 0" |
| 2007 | 90°F | 60°F | 0" | 0" |
| 2006 | 67°F | 47°F | 0" | 0" |
| 2005 | 82°F | 59°F | 0" | 0" |
| 2004 | 82°F | 47°F | 0" | 0" |
| 2003 | 76°F | 55°F | 0" | 0" |
| 2002 | 70°F | 56°F | 0.38" | 0" |
| 2001 | 81°F | 57°F | 0.58" | 0" |
| 2000 | 76°F | 46°F | 0.18" | 0" |
| 1999 | 69°F | 48°F | 0.03" | 0" |
| 1998 | 89°F | 69°F | 0" | 0" |
| 1997 | 67°F | 56°F | 0" | 0" |
| 1996 | 78°F | 59°F | 0" | 0" |
| 1995 | 61°F | 48°F | 0.1" | 0" |
| 1994 | 83°F | 52°F | 0" | 0" |
| 1993 | 79°F | 57°F | 0" | 0" |
| 1992 | 78°F | 70°F | 0.58" | 0" |
| 1990 | 75°F | 51°F | 1.27" | 0" |
| 1989 | 78°F | 56°F | 0" | 0" |
| 1988 | 86°F | 67°F | 0" | 0" |
| 1987 | 74°F | 44°F | 0" | 0" |
| 1986 | 91°F | 65°F | 0" | 0" |
| 1985 | 84°F | 57°F | 0" | 0" |
| 1982 | 67°F | 47°F | 0" | 0" |
| 1981 | 83°F | 59°F | 0" | 0" |
| 1980 | 90°F | 64°F | 0" | 0" |
| 1979 | -- | 52°F | 0" | 0" |
| 1978 | 93°F | 59°F | 1.42" | 0" |
| 1977 | 72°F | 50°F | 0" | 0" |
| 1976 | 69°F | 47°F | 0.03" | 0" |
| 1975 | 68°F | 46°F | 0" | 0" |
| 1974 | 75°F | 55°F | 0" | 0" |
| 1973 | 67°F | 61°F | 0.05" | 0" |
| 1972 | 93°F | 67°F | 0.53" | 0" |
| 1971 | 60°F | -- | 0" | 0" |