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° | — | — |
Naperville, IL Temperature Range by Month
Average monthly highs and lows. The shaded band shows the typical daily temperature range.
Naperville, IL Monthly Precipitation
Average rainfall and snowfall per month, in inches.
Naperville, IL 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 Naperville, IL
Naperville, IL has no months that meet our "pleasant" threshold — every season has tradeoffs.