Weather on September 21
Philadelphia, PA
55 Years of Data
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.
| 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° | — | — |
Philadelphia, PA Temperature Range by Month
Average monthly highs and lows. The shaded band shows the typical daily temperature range.
Philadelphia, PA Monthly Precipitation
Average rainfall and snowfall per month, in inches.
Philadelphia, PA Daily Temperature Calendar
Average daily high temperature for every day of the year. Each cell is the climatological mean for that calendar day across 55 years of NOAA data.
Best Time to Visit Philadelphia, PA
Philadelphia, PA has no months that meet our "pleasant" threshold — every season has tradeoffs.