Weather on September 20
Allentown, PA
55 Years of Data
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" | — |
Allentown, PA Temperature Range by Month
Average monthly highs and lows. The shaded band shows the typical daily temperature range.
Allentown, PA Monthly Precipitation
Average rainfall and snowfall per month, in inches.
Allentown, 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 Allentown, PA
Allentown, PA has no months that meet our "pleasant" threshold — every season has tradeoffs.