August is one of the warmer months of the year in Chicago, with average highs near 24.5°C and lows around 19.3°C (mean 21.9°C). It is a relatively wet time of year, averaging 103 mm of rainfall and 77% relative humidity across the period.
August is one of the warmer months of the year in Chicago. Across 45 years of records, the warmest August in Chicago was 2021 — when the month averaged 24.4°C — while the coldest was 1982 at 17.9°C. Typical August days reach 24.5°C with nights near 19.3°C. The long-term trend is warming, about 0.7°C per decade.
August is a relatively wet time of year in Chicago, averaging 103 mm of rainfall. The wettest August on record was 2007 with 278 mm, while the driest was 2017 at 50 mm.
Relative humidity in Chicago during August averages 77%. The most humid August was 1995 at 85%, and the least humid was 2012 at 67%.
August receives about 5.3 kWh/m²/day of solar energy in Chicago. The sunniest August was 2020 at 6 kWh/m²/day, and the cloudiest was 1987 at 4.7.
Average wind speed in Chicago during August is 3.3 m/s. The windiest August was 2009 at 4.1 m/s, while the calmest was 1995 at 2.7 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 20.4°C | 21.3°C | 22.2°C | 22.7°C | 23.2°C | +2.8°C |
| Avg High | 23.4°C | 23.8°C | 24.8°C | 25.2°C | 25.7°C | +2.3°C |
| Avg Low | 17.4°C | 18.7°C | 19.7°C | 20.3°C | 20.6°C | +3.2°C |
| Avg Rain | 109 mm | 105 mm | 116 mm | 96 mm | 78 mm | -31 mm |
August temperatures in Chicago have risen by about 3.2°C between 1981–1985 and 2021–2025.
August has ranged from a record low of 10°C (1986) to a record high of 33°C (1988).
Rainfall in August is a relatively wet time of year, averaging 103 mm, with a wettest year of 278 mm.
Daytime highs and overnight lows have shifted differently — highs rose about 0.6°C per decade while lows rose 0.9°C per decade, narrowing the gap between day and night.
One of the best times to visit Chicago
August is one of the best times to visit Chicago. Expect days averaging 24.5°C and nights around 19.3°C (mean 21.9°C) — warmer than Chicago's yearly average — with higher rainfall (103 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 | 25.3°C | 23.0°C | 20.6°C | 31.0°C | 15.8°C | 102 mm | 71% | 3.3 m/s | 5.9 |
| 2024 | 26.0°C | 23.3°C | 20.5°C | 32.5°C | 16.6°C | 78 mm | 73% | 3.3 m/s | 5.6 |
| 2023 | 25.0°C | 22.3°C | 19.6°C | 32.2°C | 17.3°C | 73 mm | 75% | 3.8 m/s | 5.3 |
| 2022 | 25.3°C | 22.7°C | 20.1°C | 30.2°C | 17.8°C | 68 mm | 76% | 3.4 m/s | 5.3 |
| 2021 🔥 | 26.9°C | 24.4°C | 22.0°C | 30.0°C | 19.4°C | 90 mm | 75% | 3 m/s | 5.7 |
| 2020 | 25.9°C | 23.3°C | 20.7°C | 30.6°C | 17.6°C | 55 mm | 73% | 3.1 m/s | 6 |
| 2019 | 24.6°C | 22.3°C | 20.1°C | 27.2°C | 16.1°C | 87 mm | 78% | 3.4 m/s | 5.6 |
| 2018 | 26.0°C | 23.5°C | 21.1°C | 30.0°C | 18.0°C | 118 mm | 79% | 3.4 m/s | 5.2 |
| 2017 | 24.0°C | 21.4°C | 18.8°C | 28.2°C | 14.7°C | 50 mm | 74% | 3.3 m/s | 5.4 |
| 2016 | 25.9°C | 23.9°C | 21.8°C | 29.7°C | 17.3°C | 143 mm | 79% | 3 m/s | 5.2 |
| 2015 | 24.9°C | 22.0°C | 19.2°C | 28.5°C | 15.0°C | 103 mm | 77% | 3.4 m/s | 5.3 |
| 2014 | 24.4°C | 22.0°C | 19.7°C | 26.7°C | 15.8°C | 142 mm | 82% | 2.8 m/s | 4.8 |
| 2013 | 24.5°C | 22.0°C | 19.4°C | 29.7°C | 15.5°C | 65 mm | 77% | 3.1 m/s | 5.4 |
| 2012 | 26.1°C | 23.1°C | 20.1°C | 30.7°C | 17.1°C | 97 mm | 67% | 3.2 m/s | 5.6 |
| 2011 | 25.4°C | 23.1°C | 20.8°C | 29.4°C | 18.2°C | 87 mm | 76% | 3.4 m/s | 5.7 |
| 2010 | 26.5°C | 24.1°C | 21.6°C | 30.0°C | 18.0°C | 63 mm | 79% | 3.2 m/s | 5.7 |
| 2009 | 23.3°C | 20.9°C | 18.4°C | 28.0°C | 13.9°C | 132 mm | 80% | 4.1 m/s | 5 |
| 2008 | 24.5°C | 22.1°C | 19.7°C | 27.8°C | 17.1°C | 56 mm | 76% | 3.4 m/s | 5.8 |
| 2007 🌧️ | 25.5°C | 23.2°C | 21.0°C | 29.4°C | 17.9°C | 278 mm | 81% | 3.2 m/s | 5 |
| 2006 | 25.4°C | 23.0°C | 20.7°C | 32.4°C | 17.6°C | 126 mm | 75% | 3.7 m/s | 4.8 |
| 2005 | 26.9°C | 24.1°C | 21.4°C | 31.5°C | 18.2°C | 58 mm | 70% | 3.3 m/s | 5.3 |
| 2004 | 22.7°C | 20.2°C | 17.6°C | 28.6°C | 13.0°C | 110 mm | 76% | 3.7 m/s | 5 |
| 2003 | 25.1°C | 22.3°C | 19.6°C | 31.8°C | 17.4°C | 51 mm | 78% | 3.4 m/s | 5.5 |
| 2002 | 24.9°C | 22.2°C | 19.6°C | 30.8°C | 16.4°C | 131 mm | 77% | 3.5 m/s | 5.4 |
| 2001 | 25.1°C | 22.3°C | 19.6°C | 32.2°C | 16.6°C | 154 mm | 77% | 3.4 m/s | 5.3 |
| 2000 | 24.7°C | 22.1°C | 19.4°C | 29.3°C | 16.8°C | 69 mm | 77% | 3.6 m/s | 5.6 |
| 1999 | 23.9°C | 21.4°C | 19.0°C | 27.3°C | 16.1°C | 82 mm | 74% | 3.7 m/s | 5.2 |
| 1998 | 25.9°C | 23.6°C | 21.2°C | 29.7°C | 18.1°C | 108 mm | 77% | 3.3 m/s | 5.2 |
| 1997 | 23.1°C | 20.5°C | 18.0°C | 29.0°C | 15.7°C | 115 mm | 79% | 3.6 m/s | 4.9 |
| 1996 | 23.9°C | 21.5°C | 19.0°C | 27.4°C | 16.4°C | 52 mm | 78% | 2.9 m/s | 5.6 |
| 1995 | 26.1°C | 23.7°C | 21.4°C | 30.3°C | 17.7°C | 113 mm | 85% | 2.7 m/s | 5.1 |
| 1994 | 21.8°C | 19.0°C | 16.3°C | 26.9°C | 13.8°C | 113 mm | 82% | 3.7 m/s | 4.8 |
| 1993 | 24.0°C | 21.7°C | 19.5°C | 28.2°C | 15.4°C | 144 mm | 85% | 3.2 m/s | 4.9 |
| 1992 | 21.9°C | 19.0°C | 16.1°C | 26.9°C | 12.8°C | 69 mm | 76% | 3.6 m/s | 5.2 |
| 1991 | 24.7°C | 21.7°C | 18.7°C | 29.9°C | 17.1°C | 82 mm | 74% | 3.3 m/s | 5.5 |
| 1990 | 23.0°C | 20.4°C | 17.9°C | 27.4°C | 14.3°C | 173 mm | 83% | 3.2 m/s | 5.2 |
| 1989 | 23.4°C | 20.5°C | 17.6°C | 26.3°C | 13.2°C | 132 mm | 79% | 3.2 m/s | 5.2 |
| 1988 | 27.1°C | 23.8°C | 20.4°C | 33.0°C | 14.7°C | 99 mm | 69% | 3.7 m/s | 5.3 |
| 1987 | 23.0°C | 20.5°C | 18.0°C | 30.3°C | 13.7°C | 249 mm | 80% | 3.5 m/s | 4.7 |
| 1986 | 22.0°C | 19.0°C | 16.0°C | 25.4°C | 10.0°C | 67 mm | 74% | 3.4 m/s | 5.2 |
| 1985 | 22.0°C | 19.2°C | 16.3°C | 25.3°C | 14.1°C | 100 mm | 78% | 3.1 m/s | 4.9 |
| 1984 | 24.3°C | 20.7°C | 17.1°C | 30.7°C | 13.2°C | 56 mm | 76% | 3.1 m/s | 5.4 |
| 1983 | 24.0°C | 20.5°C | 17.1°C | 28.4°C | 14.4°C | 78 mm | 80% | 2.9 m/s | — |
| 1982 ❄️ | 21.0°C | 17.9°C | 14.8°C | 25.8°C | 11.7°C | 72 mm | 80% | 3 m/s | — |
| 1981 | 23.9°C | 21.4°C | 18.9°C | 26.7°C | 15.7°C | 125 mm | 80% | 3.4 m/s | — |
Actual recorded August data for each year, 1981–2025 — sourced from NASA POWER.
The average high in August is around 24.5°C with lows near 19.3°C (mean 21.9°C), based on 45 years of NASA POWER data.
August averages 103 mm of rainfall in Chicago, a relatively wet time of year. The wettest on record was 278 mm in 2007.
The hottest August reached 33°C in 1988. The coldest dipped to 10°C in 1986.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average August temperatures have risen by about 3.2°C. Daytime highs moved from 23°C to 25.7°C and overnight lows from 16.8°C to 20.6°C over the same span.
August is one of the warmer months of the year in Chicago and a relatively wet time of year, so plan for around 24.5°C daytime highs and 19.3°C at night.
Not quite — August is the 12th coolest month in Chicago, averaging 21.9°C.
For August in Chicago, pack light layers you can adjust through the day, with typical highs of 24.5°C and lows of 19.3°C. Bring an umbrella or light rain jacket too.
Relative humidity in August averages 77% — quite humid.
Average wind speed in August is 3.3 m/s. The windiest August on record averaged 4.1 m/s (2009).
The wettest August on record was 2007 with 278 mm. On average, August sees 103 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 Chicago 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.
