Weather on September 20
Joliet, IL
55 Years of Data
Avg High
77°F
Avg Low
55°F
Warmest
1978
81°F avg
Coldest
2006
49°F avg
About This Date
September 20th in Joliet, IL typically brings pleasant fall weather, with average highs around 77°F and lows near 55°F. Over 54 years of records, the warmest September 20th was in 1978 (81°F average), while the coldest was 2006 (49°F) — a 32°F range across recorded history. Rain or other precipitation has occurred on about 35% of September 20th dates historically, with the wettest September 20th recording 4.85" 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 Joliet, IL? Great weather for outdoor activities. Consider bringing rain gear or an umbrella.
Warming Trend
0.9°F per decade on this date
| Year | High | Low | Avg | Precip | Snow |
|---|---|---|---|---|---|
| 2025 | 77° | 64° | 71° | 0.91" | — |
| 2024 | 90° | 57° | 73° | — | — |
| 2023 | 68° | 54° | 61° | 2.54" | — |
| 2022 | 80° | 60° | 70° | 0.13" | — |
| 2021 | 89° | 66° | 78° | — | — |
| 2020 | 66° | 45° | 55° | — | — |
| 2019 | 83° | 60° | 71° | 1.02" | — |
| 2018 | 82° | 65° | 73° | — | — |
| 2017 | 80° | 63° | 71° | — | — |
| 2016 | 86° | 57° | 72° | — | — |
| 2015 | 70° | 50° | 60° | 0.05" | — |
| 2014 | 74° | 52° | 63° | — | — |
| 2013 | 90° | 67° | 78° | 0.38" | — |
| 2012 | 72° | 43° | 57° | — | — |
| 2011 | 67° | 50° | 58° | — | — |
| 2010 | 70° | 56° | 63° | — | — |
| 2009 | 76° | 55° | 65° | — | — |
| 2008 | 80° | 56° | 68° | — | — |
| 2007 | 88° | 64° | 76° | — | — |
| 2006coldest | 55° | 43° | 49° | — | — |
| 2005 | 84° | 61° | 72° | 0.3" | — |
| 2004 | 78° | 54° | 66° | — | — |
| 2003 | 78° | 46° | 62° | — | — |
| 2002 | 86° | 70° | 78° | 1.14" | — |
| 2001 | 71° | 53° | 62° | 0.08" | — |
| 2000 | 90° | 62° | 76° | 0.36" | — |
| 1999 | 77° | 52° | 64° | 0.1" | — |
| 1998 | 87° | 67° | 77° | — | — |
| 1997 | 87° | 61° | 74° | 0.38" | — |
| 1996 | 76° | 49° | 62° | — | — |
| 1995 | 72° | 53° | 62° | 0.05" | — |
| 1994 | 84° | 55° | 70° | — | — |
| 1993 | 66° | 50° | 58° | — | — |
| 1992 | 66° | 44° | 55° | — | — |
| 1991 | 61° | 39° | 50° | — | — |
| 1990 | 62° | 48° | 55° | — | — |
| 1989 | 80° | 54° | 67° | — | — |
| 1988 | 75° | 56° | 65° | 1.19" | — |
| 1987 | 71° | 53° | 62° | — | — |
| 1986 | 73° | 64° | 69° | 4.85" | — |
| 1985 | 86° | 61° | 73° | — | — |
| 1984 | 88° | 50° | 69° | — | — |
| 1983 | 86° | 62° | 74° | 0.38" | — |
| 1982 | 72° | 44° | 58° | — | — |
| 1981 | 77° | 47° | 62° | — | — |
| 1980 | 83° | 53° | 68° | 0.05" | — |
| 1979 | 69° | 44° | 57° | — | — |
| 1978warmest | 92° | 70° | 81° | — | — |
| 1977 | 70° | 49° | 59° | — | — |
| 1976 | 83° | 59° | 71° | 0.79" | — |
| 1975 | 66° | 48° | 57° | — | — |
| 1974 | 84° | 57° | 71° | — | — |
| 1973 | 68° | 53° | 61° | — | — |
| 1971 | 66° | 50° | 58° | 0.05" | — |
54 years of data from JOLIET