August is one of the warmer months of the year in Naperville, with average highs near 28.1°C and lows around 16.9°C (mean 22.5°C). It is a relatively wet time of year, averaging 104 mm of rainfall and 72% relative humidity across the period.
August is one of the warmer months of the year in Naperville. Across 45 years of records, the warmest August in Naperville was 1988 — when the month averaged 25°C — while the coldest was 1992 at 19.4°C. Typical August days reach 28.1°C with nights near 16.9°C. The long-term trend is warming, about 0.3°C per decade.
August is a relatively wet time of year in Naperville, averaging 104 mm of rainfall. The wettest August on record was 2007 with 288 mm, while the driest was 2020 at 44 mm.
Relative humidity in Naperville during August averages 72%. The most humid August was 1993 at 81%, and the least humid was 1988 at 60%.
August receives about 5.4 kWh/m²/day of solar energy in Naperville. The sunniest Augusts were 2011 and 2020 at 6 kWh/m²/day, and the cloudiest was 1993 at 4.7.
Average wind speed in Naperville during August is 2.4 m/s. The windiest August was 2009 at 2.9 m/s, while the calmest was 2014 at 2 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 22.1°C | 21.9°C | 22.7°C | 22.6°C | 23.3°C | +1.2°C |
| Avg High | 27.9°C | 27.4°C | 28.4°C | 27.9°C | 29.1°C | +1.2°C |
| Avg Low | 16.2°C | 16.5°C | 17.0°C | 17.2°C | 17.6°C | +1.4°C |
| Avg Rain | 117 mm | 102 mm | 116 mm | 97 mm | 81 mm | -37 mm |
August temperatures in Naperville have risen by about 1.2°C between 1981–1985 and 2021–2025.
August has ranged from a record low of 5.6°C (1986) to a record high of 39°C (1988).
Rainfall in August is a relatively wet time of year, averaging 104 mm, with a wettest year of 288 mm.
One of the best times to visit Naperville
August is one of the best times to visit Naperville. Expect days averaging 28.1°C and nights around 16.9°C (mean 22.5°C) — warmer than Naperville's yearly average — with higher rainfall (104 mm), so conditions are generally comfortable for sightseeing and outdoor plans.
| Year | Avg High | Avg Temp | Avg Low | Hottest Day | Coldest Day | Rainfall | Humidity | Wind | Solar |
|---|---|---|---|---|---|---|---|---|---|
| 2025 | 28.1°C | 22.5°C | 17.0°C | 34.5°C | 10.1°C | 112 mm | 71% | 2.2 m/s | 5.9 |
| 2024 | 29.1°C | 23.3°C | 17.5°C | 35.5°C | 11.9°C | 74 mm | 68% | 2.4 m/s | 5.6 |
| 2023 | 29.2°C | 23.1°C | 16.9°C | 38.3°C | 12.0°C | 60 mm | 69% | 2.6 m/s | 5.5 |
| 2022 | 28.7°C | 22.9°C | 17.2°C | 34.3°C | 13.7°C | 96 mm | 72% | 2.4 m/s | 5.2 |
| 2021 | 30.4°C | 24.9°C | 19.4°C | 33.5°C | 14.7°C | 97 mm | 71% | 2.2 m/s | 5.6 |
| 2020 | 28.9°C | 23.2°C | 17.4°C | 34.5°C | 11.5°C | 44 mm | 70% | 2.2 m/s | 6 |
| 2019 | 27.0°C | 21.9°C | 16.8°C | 30.2°C | 12.4°C | 89 mm | 76% | 2.2 m/s | 5.6 |
| 2018 | 28.8°C | 23.5°C | 18.3°C | 33.9°C | 12.9°C | 119 mm | 75% | 2.3 m/s | 5.1 |
| 2017 | 26.0°C | 20.5°C | 15.1°C | 30.9°C | 10.7°C | 55 mm | 73% | 2.3 m/s | 5.5 |
| 2016 | 28.4°C | 23.7°C | 19.1°C | 33.3°C | 13.4°C | 131 mm | 77% | 2.1 m/s | 5.3 |
| 2015 | 27.6°C | 21.9°C | 16.2°C | 32.2°C | 11.4°C | 87 mm | 73% | 2.5 m/s | 5.5 |
| 2014 | 27.2°C | 22.3°C | 17.3°C | 29.9°C | 10.2°C | 154 mm | 79% | 2 m/s | 4.9 |
| 2013 | 28.0°C | 22.4°C | 16.7°C | 34.6°C | 11.6°C | 67 mm | 73% | 2.3 m/s | 5.6 |
| 2012 | 30.0°C | 23.4°C | 16.7°C | 36.1°C | 11.4°C | 83 mm | 61% | 2.2 m/s | 5.7 |
| 2011 | 27.5°C | 22.4°C | 17.4°C | 32.3°C | 13.2°C | 107 mm | 76% | 2.1 m/s | 6 |
| 2010 | 28.7°C | 23.7°C | 18.7°C | 32.6°C | 13.1°C | 76 mm | 78% | 2.2 m/s | 5.8 |
| 2009 | 25.7°C | 20.6°C | 15.5°C | 31.4°C | 7.8°C | 141 mm | 78% | 2.9 m/s | 5 |
| 2008 | 27.8°C | 22.1°C | 16.3°C | 32.5°C | 13.0°C | 53 mm | 72% | 2.3 m/s | 5.8 |
| 2007 🌧️ | 28.2°C | 23.4°C | 18.6°C | 33.6°C | 12.4°C | 288 mm | 79% | 2.3 m/s | 5.1 |
| 2006 | 29.2°C | 23.5°C | 17.9°C | 37.7°C | 13.5°C | 107 mm | 69% | 2.6 m/s | 4.8 |
| 2005 | 30.6°C | 24.4°C | 18.2°C | 36.6°C | 14.3°C | 74 mm | 62% | 2.3 m/s | 5.4 |
| 2004 | 25.9°C | 20.2°C | 14.6°C | 32.8°C | 9.1°C | 114 mm | 71% | 2.7 m/s | 5 |
| 2003 | 29.7°C | 23.7°C | 17.8°C | 38.0°C | 15.1°C | 54 mm | 69% | 2.4 m/s | 5.5 |
| 2002 | 29.1°C | 23.2°C | 17.2°C | 35.4°C | 11.3°C | 141 mm | 70% | 2.4 m/s | 5.5 |
| 2001 | 29.4°C | 23.4°C | 17.4°C | 37.0°C | 13.1°C | 129 mm | 69% | 2.4 m/s | 5.4 |
| 2000 | 28.6°C | 22.6°C | 16.6°C | 35.2°C | 12.0°C | 63 mm | 72% | 2.5 m/s | 5.6 |
| 1999 | 27.5°C | 21.7°C | 16.0°C | 33.4°C | 11.6°C | 73 mm | 69% | 2.6 m/s | 5.1 |
| 1998 | 28.7°C | 23.4°C | 18.2°C | 33.6°C | 14.6°C | 117 mm | 74% | 2.2 m/s | 5.2 |
| 1997 | 26.8°C | 21.1°C | 15.3°C | 34.0°C | 11.5°C | 112 mm | 73% | 2.6 m/s | 4.9 |
| 1996 | 27.3°C | 21.8°C | 16.3°C | 31.1°C | 13.2°C | 63 mm | 75% | 2.1 m/s | 5.6 |
| 1995 | 29.6°C | 24.8°C | 19.9°C | 34.5°C | 14.7°C | 117 mm | 80% | 2.1 m/s | 5.2 |
| 1994 | 25.4°C | 19.9°C | 14.4°C | 31.5°C | 9.3°C | 128 mm | 77% | 2.6 m/s | 4.8 |
| 1993 | 27.0°C | 22.3°C | 17.7°C | 32.1°C | 11.8°C | 124 mm | 81% | 2.4 m/s | 4.7 |
| 1992 ❄️ | 25.3°C | 19.4°C | 13.4°C | 31.2°C | 10.1°C | 77 mm | 71% | 2.6 m/s | 5.3 |
| 1991 | 29.6°C | 23.4°C | 17.3°C | 36.1°C | 13.7°C | 65 mm | 64% | 2.4 m/s | 5.4 |
| 1990 | 26.7°C | 21.6°C | 16.4°C | 31.6°C | 11.4°C | 147 mm | 78% | 2.3 m/s | 5.4 |
| 1989 | 27.0°C | 21.4°C | 15.7°C | 31.3°C | 9.2°C | 153 mm | 74% | 2.3 m/s | 5.3 |
| 1988 🔥 | 31.5°C | 25.0°C | 18.6°C | 39.0°C | 9.9°C | 94 mm | 60% | 2.8 m/s | 5.4 |
| 1987 | 26.5°C | 21.5°C | 16.5°C | 35.8°C | 8.7°C | 276 mm | 76% | 2.6 m/s | 4.8 |
| 1986 | 25.8°C | 19.9°C | 13.9°C | 30.8°C | 5.6°C | 62 mm | 68% | 2.5 m/s | 5.3 |
| 1985 | 26.9°C | 21.0°C | 15.0°C | 32.1°C | 10.4°C | 93 mm | 70% | 2.4 m/s | 5.1 |
| 1984 | 29.9°C | 23.3°C | 16.8°C | 36.9°C | 10.7°C | 58 mm | 65% | 2.4 m/s | 5.5 |
| 1983 | 30.5°C | 24.3°C | 18.1°C | 36.4°C | 13.7°C | 83 mm | 70% | 2.3 m/s | — |
| 1982 | 26.3°C | 20.5°C | 14.7°C | 32.3°C | 7.8°C | 72 mm | 73% | 2.4 m/s | — |
| 1981 | 26.6°C | 21.6°C | 16.5°C | 30.6°C | 11.5°C | 166 mm | 78% | 2.3 m/s | — |
Actual recorded August data for each year, 1981–2025 — sourced from NASA POWER.
The average high in August is around 28.1°C with lows near 16.9°C (mean 22.5°C), based on 45 years of NASA POWER data.
August averages 104 mm of rainfall in Naperville, a relatively wet time of year. The wettest on record was 288 mm in 2007.
The hottest August reached 39°C in 1988. The coldest dipped to 5.6°C in 1986.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average August temperatures have risen by about 1.2°C. Daytime highs moved from 28°C to 29.1°C and overnight lows from 16.2°C to 17.6°C over the same span.
August is one of the warmer months of the year in Naperville and a relatively wet time of year, so plan for around 28.1°C daytime highs and 16.9°C at night.
Not quite — August is the 11th coolest month in Naperville, averaging 22.5°C.
For August in Naperville, pack light layers you can adjust through the day, with typical highs of 28.1°C and lows of 16.9°C. Bring an umbrella or light rain jacket too.
Relative humidity in August averages 72% — moderately humid.
Average wind speed in August is 2.4 m/s. The windiest August on record averaged 2.9 m/s (2009).
The wettest August on record was 2007 with 288 mm. On average, August sees 104 mm.
All figures are derived from NASA POWER (Prediction Of Worldwide Energy Resources), based on MERRA-2 satellite reanalysis, covering 1981–2025.
Explore how the weather in Naperville behaves each August, based on 45 years of NASA POWER climate data from 1981 to 2025. This page breaks down average temperatures, rainfall, humidity, wind and solar radiation for August specifically, along with year-by-year records and how the month has changed over the decades.
