Weather on September 20
Allentown, PA
55 Years of Data
Avg High
75°F
Avg Low
53°F
Warmest
2017
76°F avg
Coldest
2020
49°F avg
About This Date
September 20th in Allentown, PA typically brings pleasant fall weather, with average highs around 75°F and lows near 53°F. Over 55 years of records, the warmest September 20th was in 2017 (76°F average), while the coldest was 2020 (49°F) — a 27°F range across recorded history. Rain or other precipitation has occurred on about 25% of September 20th dates historically, with the wettest September 20th recording 4.37" 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 20th in Allentown, PA? Great weather for outdoor activities.
| Year | High | Low | Avg | Precip | Snow |
|---|---|---|---|---|---|
| 2025 | 77° | 53° | 65° | — | — |
| 2024 | 83° | 56° | 69° | — | — |
| 2023 | 74° | 48° | 61° | — | — |
| 2022 | 77° | 57° | 67° | — | — |
| 2021 | 77° | 50° | 64° | — | — |
| 2020coldest | 63° | 36° | 49° | — | — |
| 2019 | 79° | 43° | 61° | — | — |
| 2018 | 72° | 64° | 68° | — | — |
| 2017warmest | 87° | 65° | 76° | — | — |
| 2016 | 85° | 64° | 74° | — | — |
| 2015 | 77° | 56° | 66° | — | — |
| 2014 | 78° | 56° | 67° | — | — |
| 2013 | 79° | 47° | 63° | — | — |
| 2012 | 72° | 45° | 58° | — | — |
| 2011 | 71° | 58° | 64° | 0.13" | — |
| 2010 | 73° | 49° | 61° | — | — |
| 2009 | 72° | 41° | 56° | — | — |
| 2008 | 70° | 41° | 55° | — | — |
| 2007 | 83° | 48° | 65° | — | — |
| 2006 | 66° | 47° | 56° | — | — |
| 2005 | 82° | 63° | 72° | — | — |
| 2004 | 72° | 43° | 57° | — | — |
| 2003 | 79° | 57° | 68° | — | — |
| 2002 | 81° | 63° | 72° | — | — |
| 2001 | 69° | 65° | 67° | 3.76" | — |
| 2000 | 81° | 54° | 67° | 0.03" | — |
| 1999 | 73° | 51° | 62° | 0.25" | — |
| 1998 | 79° | 56° | 67° | — | — |
| 1997 | 80° | 54° | 67° | 0.36" | — |
| 1996 | 75° | 45° | 60° | — | — |
| 1995 | 73° | 60° | 67° | — | — |
| 1994 | 76° | 46° | 61° | — | — |
| 1993 | 62° | 37° | 50° | — | — |
| 1992 | 73° | 44° | 59° | — | — |
| 1991 | 65° | 48° | 56° | — | — |
| 1990 | 67° | 48° | 57° | — | — |
| 1989 | 80° | 65° | 72° | 4.37" | — |
| 1988 | 79° | 67° | 73° | 0.15" | — |
| 1987 | 64° | 55° | 60° | — | — |
| 1986 | 74° | 50° | 62° | 0.08" | — |
| 1985 | 84° | 54° | 69° | — | — |
| 1984 | 81° | 53° | 67° | — | — |
| 1983 | 92° | 58° | 75° | — | — |
| 1982 | 60° | 52° | 56° | 0.43" | — |
| 1981 | 70° | 51° | 60° | — | — |
| 1980 | 81° | 55° | 68° | — | — |
| 1979 | 66° | 38° | 52° | — | — |
| 1978 | 77° | 58° | 67° | — | — |
| 1977 | 79° | 57° | 68° | 1.02" | — |
| 1976 | 77° | 55° | 66° | 0.1" | — |
| 1975 | 81° | 64° | 72° | 0.46" | — |
| 1974 | 78° | 62° | 70° | 0.61" | — |
| 1973 | 71° | 45° | 58° | — | — |
| 1972 | 64° | 54° | 59° | — | — |
| 1971 | 79° | 64° | 71° | 0.08" | — |
55 years of data from ALLENTOWN LEHIGH VLY INTL AP