Weather on September 21
Philadelphia, PA
55 Years of Data
Avg High
77°F
Avg Low
61°F
Warmest
1989
81°F avg
Coldest
2020
57°F avg
About This Date
September 21st in Philadelphia, PA typically brings pleasant fall weather, with average highs around 77°F and lows near 61°F. Over 55 years of records, the warmest September 21st was in 1989 (81°F average), while the coldest was 2020 (57°F) — a 24°F range across recorded history. Rain or other precipitation has occurred on about 13% of September 21st dates historically, with the wettest September 21st recording 1.88" 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 Philadelphia, PA? Great weather for outdoor activities.
Warming Trend
0.9°F per decade on this date
| Year | High | Low | Avg | Precip | Snow |
|---|---|---|---|---|---|
| 2025 | 77° | 60° | 69° | — | — |
| 2024 | 84° | 66° | 75° | — | — |
| 2023 | 79° | 57° | 68° | — | — |
| 2022 | 82° | 64° | 73° | — | — |
| 2021 | 80° | 63° | 71° | — | — |
| 2020coldest | 65° | 49° | 57° | — | — |
| 2019 | 80° | 61° | 70° | — | — |
| 2018 | 74° | 67° | 70° | — | — |
| 2017 | 87° | 70° | 78° | — | — |
| 2016 | 82° | 68° | 75° | — | — |
| 2015 | 79° | 59° | 69° | — | — |
| 2014 | 80° | 66° | 73° | — | — |
| 2013 | 80° | 61° | 70° | — | — |
| 2012 | 76° | 55° | 65° | — | — |
| 2011 | 77° | 63° | 70° | 0.1" | — |
| 2010 | 77° | 52° | 64° | — | — |
| 2009 | 74° | 65° | 69° | — | — |
| 2008 | 82° | 62° | 72° | — | — |
| 2007 | 85° | 64° | 74° | — | — |
| 2006 | 69° | 52° | 60° | — | — |
| 2005 | 89° | 65° | 77° | — | — |
| 2004 | 83° | 57° | 70° | — | — |
| 2003 | 79° | 66° | 72° | — | — |
| 2002 | 89° | 71° | 80° | — | — |
| 2001 | 82° | 69° | 76° | — | — |
| 2000 | 77° | 62° | 70° | — | — |
| 1999 | 66° | 50° | 58° | 1.09" | — |
| 1998 | 89° | 72° | 80° | 0.25" | — |
| 1997 | 67° | 50° | 58° | — | — |
| 1996 | 79° | 58° | 68° | — | — |
| 1995 | 82° | 67° | 74° | — | — |
| 1994 | 79° | 56° | 67° | — | — |
| 1993 | 63° | 55° | 59° | 1.88" | — |
| 1992 | 74° | 62° | 68° | — | — |
| 1991 | 66° | 51° | 59° | — | — |
| 1990 | 71° | 54° | 62° | — | — |
| 1989warmest | 89° | 74° | 81° | — | — |
| 1988 | 77° | 64° | 71° | — | — |
| 1987 | 73° | 60° | 67° | — | — |
| 1986 | 80° | 62° | 71° | — | — |
| 1985 | 82° | 65° | 73° | — | — |
| 1984 | 81° | 67° | 74° | — | — |
| 1983 | 80° | 60° | 70° | — | — |
| 1982 | 66° | 57° | 62° | — | — |
| 1981 | 76° | 58° | 67° | — | — |
| 1980 | 88° | 67° | 77° | — | — |
| 1979 | 68° | 58° | 63° | — | — |
| 1978 | 82° | 60° | 71° | — | — |
| 1977 | 67° | 57° | 62° | — | — |
| 1976 | 68° | 60° | 64° | 0.03" | — |
| 1975 | 72° | 62° | 67° | 0.15" | — |
| 1974 | 81° | 57° | 69° | 0.69" | — |
| 1973 | 64° | 52° | 58° | — | — |
| 1972 | 63° | 54° | 58° | — | — |
| 1971 | 75° | 62° | 69° | — | — |
55 years of data from PHILADELPHIA WSFO