Weather on September 21
Naperville, IL
55 Years of Data
About This Date
September 21st in Naperville, IL typically brings pleasant fall weather, with average highs around 76°F and lows near 51°F — a 25°F daily swing. Over 55 years of records, the warmest September 21st was in 2018 (80°F average), while the coldest was 1983 (46°F) — a 34°F range across recorded history. Rain or other precipitation has occurred on about 42% of September 21st dates historically, with the wettest September 21st recording 1.73" of rain. The last decade has been 10.4°F warmer on this date compared to 20-30 years ago.
The last decade has been 10.4°F warmer on this date compared to 20-30 years ago.
Planning for September 21st in Naperville, IL? Great weather for outdoor activities. Consider bringing rain gear or an umbrella.
| Year | High | Low | Avg | Precip | Snow |
|---|---|---|---|---|---|
| 2025 | 78° | 64° | 71° | 0.25" | — |
| 2024 | 89° | 54° | 71° | — | — |
| 2023 | 78° | 58° | 68° | — | — |
| 2022 | 93° | 62° | 78° | 1.07" | — |
| 2021 | 82° | 64° | 73° | 1.14" | — |
| 2020 | 72° | — | — | — | — |
| 2019 | 85° | 66° | 75° | — | — |
| 2018warmest | 92° | 68° | 80° | — | — |
| 2017 | 91° | 64° | 78° | — | — |
| 2016 | 84° | 59° | 72° | — | — |
| 2015 | 72° | 45° | 58° | — | — |
| 2014 | 76° | 55° | 65° | 1.02" | — |
| 2013 | 75° | 51° | 63° | — | — |
| 2012 | 72° | 43° | 57° | — | — |
| 2011 | 75° | 50° | 63° | — | — |
| 2010 | 79° | 60° | 69° | — | — |
| 2009 | 76° | 44° | 60° | — | — |
| 2008 | 81° | 54° | 67° | — | — |
| 2007 | 81° | 57° | 69° | — | — |
| 2006 | 68° | 37° | 53° | — | — |
| 2005 | 87° | 53° | 70° | — | — |
| 2004 | 83° | 49° | 66° | — | — |
| 2003 | 76° | 43° | 59° | — | — |
| 2002 | 82° | 57° | 70° | 1.4" | — |
| 2001 | 77° | 61° | 69° | 1.73" | — |
| 2000 | 66° | 43° | 54° | 1.02" | — |
| 1999 | 67° | 46° | 56° | 0.03" | — |
| 1998 | 82° | 56° | 69° | 0.05" | — |
| 1997 | 67° | 45° | 56° | — | — |
| 1996 | 78° | 55° | 67° | 0.13" | — |
| 1995 | 56° | 44° | 50° | 0.1" | — |
| 1994 | 86° | 53° | 70° | — | — |
| 1993 | 69° | 57° | 63° | 0.1" | — |
| 1992 | 70° | 56° | 63° | 1.07" | — |
| 1991 | 67° | 37° | 52° | 0.13" | — |
| 1990 | 71° | 54° | 62° | — | — |
| 1989 | 80° | 52° | 66° | — | — |
| 1988 | 77° | 48° | 63° | 0.3" | — |
| 1987 | 60° | 43° | 51° | — | — |
| 1986 | 86° | 59° | 73° | 1.14" | — |
| 1985 | 86° | 54° | 70° | 0.18" | — |
| 1984 | 86° | 52° | 69° | 1.63" | — |
| 1983coldest | 53° | 39° | 46° | 1.63" | — |
| 1982 | 61° | 39° | 50° | — | — |
| 1981 | 77° | 52° | 64° | — | — |
| 1980 | 87° | — | — | — | — |
| 1979 | 76° | 56° | 66° | — | — |
| 1978 | 74° | 56° | 65° | 0.74" | — |
| 1977 | 68° | 40° | 54° | — | — |
| 1976 | 67° | 37° | 52° | 0.03" | — |
| 1975 | 58° | 49° | 53° | — | — |
| 1974 | 68° | 44° | 56° | — | — |
| 1973 | 70° | 40° | 55° | 0.1" | — |
| 1972 | 83° | 55° | 69° | 0.94" | — |
| 1971 | 73° | 35° | 54° | — | — |