Weather on September 21 at Biscayne
Biscayne National Park
Based on 55 years of data from Miami, FL
Planning Your Visit
September 21st in Biscayne National Park (via Miami, FL) typically brings warm fall weather, with average highs around 87°F and lows near 78°F. Over 55 years of records, the warmest September 21st was in 2011 (86°F average), while the coldest was 1981 (78°F) — a 8°F range across recorded history. Rain or other precipitation has occurred on about 44% of September 21st dates historically, with the wettest September 21st recording 5.46" of rain. Temperatures on this date have remained relatively stable over the past several decades.
Temperatures on this date have remained relatively stable over the past several decades.
Planning for September 21st in Biscayne? 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 | 86°F | 77°F | 0.71" | -- |
| 2024 | 90°F | 76°F | 0.05" | -- |
| 2023 | 89°F | 76°F | 0.38" | -- |
| 2022 | 86°F | 76°F | 0" | -- |
| 2021 | 91°F | 76°F | 0" | -- |
| 2020 | 87°F | 79°F | 0" | -- |
| 2019 | 84°F | 79°F | 0" | -- |
| 2018 | 87°F | 77°F | 0" | -- |
| 2017 | 86°F | 77°F | 0" | -- |
| 2016 | 89°F | 79°F | 0" | -- |
| 2015 | 92°F | 74°F | 1.02" | -- |
| 2014 | 87°F | 73°F | 0.76" | -- |
| 2013 | 85°F | 79°F | 0" | -- |
| 2012 | 89°F | 77°F | 0.94" | -- |
| 2011 | 89°F | 83°F | 0" | -- |
| 2010 | 88°F | 81°F | 0" | 0" |
| 2009 | 88°F | 78°F | 0" | 0" |
| 2008 | 87°F | 80°F | 0" | -- |
| 2007 | 90°F | 75°F | 0.08" | -- |
| 2006 | 89°F | 76°F | 0.23" | 0" |
| 2005 | 87°F | 74°F | 1.57" | 0" |
| 2004 | 86°F | 73°F | 0.2" | 0" |
| 2003 | 85°F | 79°F | 1.52" | 0" |
| 2002 | 88°F | 80°F | 0.03" | 0" |
| 2001 | 89°F | 76°F | 0" | 0" |
| 2000 | 88°F | 82°F | 0" | 0" |
| 1999 | 83°F | 76°F | 2.54" | 0" |
| 1998 | 87°F | 72°F | 5.46" | 0" |
| 1997 | 88°F | 78°F | 0" | 0" |
| 1996 | 90°F | 77°F | 0.38" | 0" |
| 1995 | 87°F | 83°F | 0" | 0" |
| 1994 | 86°F | 76°F | 1.27" | 0" |
| 1993 | 88°F | 82°F | 0" | 0" |
| 1992 | 89°F | 80°F | 0" | 0" |
| 1991 | 87°F | 78°F | 0.13" | 0" |
| 1990 | 88°F | 81°F | 0" | 0" |
| 1989 | 93°F | 71°F | 0" | 0" |
| 1988 | 86°F | 80°F | 0" | 0" |
| 1987 | 88°F | 80°F | 0" | 0" |
| 1986 | 84°F | 73°F | 4.17" | 0" |
| 1985 | 87°F | 73°F | 0" | 0" |
| 1984 | 83°F | 77°F | 0.48" | 0" |
| 1983 | 87°F | 81°F | 0" | 0" |
| 1982 | 87°F | 78°F | 0" | 0" |
| 1981 | 83°F | 74°F | 1.22" | 0" |
| 1980 | 85°F | 80°F | 0" | 0" |
| 1979 | 86°F | 82°F | 0.71" | 0" |
| 1978 | 85°F | 80°F | 0" | 0" |
| 1977 | 87°F | 79°F | 0.25" | 0" |
| 1976 | 88°F | 80°F | 0" | 0" |
| 1975 | 85°F | 80°F | 0.56" | 0" |
| 1974 | 85°F | 79°F | 0" | 0" |
| 1973 | 88°F | 78°F | 0" | 0" |
| 1972 | 86°F | 75°F | 0.13" | 0" |
| 1971 | 87°F | 79°F | 0" | 0" |