August is one of the warmer months of the year in Chicago Heights, with average highs near 27.6°C and lows around 17.3°C (mean 22.5°C). It is a relatively wet time of year, averaging 99 mm of rainfall and 73% relative humidity across the period.
August is one of the warmer months of the year in Chicago Heights. Across 45 years of records, the warmest August in Chicago Heights was 1988 — when the month averaged 25°C — while the coldest was 1992 at 19.4°C. Typical August days reach 27.6°C with nights near 17.3°C. The long-term trend is warming, about 0.5°C per decade.
August is a relatively wet time of year in Chicago Heights, averaging 99 mm of rainfall. The wettest August on record was 2007 with 260 mm, while the driest was 1996 at 43 mm.
Relative humidity in Chicago Heights during August averages 73%. The most humid August was 1993 at 84%, and the least humid was 1988 at 60%.
August receives about 5.3 kWh/m²/day of solar energy in Chicago Heights. The sunniest August was 2020 at 6 kWh/m²/day, and the cloudiest was 1987 at 4.7.
Average wind speed in Chicago Heights during August is 2.4 m/s. The windiest August was 2009 at 2.9 m/s, while the calmest was 1995 at 1.9 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 21.8°C | 21.7°C | 22.7°C | 22.9°C | 23.5°C | +1.7°C |
| Avg High | 27.3°C | 26.6°C | 27.8°C | 27.9°C | 28.9°C | +1.6°C |
| Avg Low | 16.3°C | 16.7°C | 17.6°C | 17.9°C | 18.1°C | +1.8°C |
| Avg Rain | 94 mm | 100 mm | 118 mm | 97 mm | 82 mm | -12 mm |
August temperatures in Chicago Heights have risen by about 1.9°C between 1981–1985 and 2021–2025.
August has ranged from a record low of 5.4°C (1986) to a record high of 38.2°C (1988).
Rainfall in August is a relatively wet time of year, averaging 99 mm, with a wettest year of 260 mm.
One of the best times to visit Chicago Heights
August is one of the best times to visit Chicago Heights. Expect days averaging 27.6°C and nights around 17.3°C (mean 22.5°C) — warmer than Chicago Heights's yearly average — with higher rainfall (99 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 | 28.0°C | 22.8°C | 17.7°C | 34.1°C | 12.0°C | 109 mm | 68% | 2.3 m/s | 5.9 |
| 2024 | 29.0°C | 23.5°C | 17.9°C | 35.0°C | 12.3°C | 84 mm | 68% | 2.4 m/s | 5.6 |
| 2023 | 28.4°C | 22.8°C | 17.3°C | 36.1°C | 11.4°C | 81 mm | 70% | 2.7 m/s | 5.3 |
| 2022 | 29.0°C | 23.5°C | 18.0°C | 33.9°C | 14.7°C | 75 mm | 70% | 2.6 m/s | 5.3 |
| 2021 | 30.0°C | 24.9°C | 19.8°C | 33.7°C | 13.6°C | 97 mm | 71% | 2.3 m/s | 5.7 |
| 2020 | 28.9°C | 23.5°C | 18.1°C | 33.7°C | 13.2°C | 46 mm | 69% | 2.2 m/s | 6 |
| 2019 | 27.1°C | 22.3°C | 17.5°C | 30.6°C | 13.2°C | 69 mm | 76% | 2.3 m/s | 5.6 |
| 2018 | 29.3°C | 24.2°C | 19.2°C | 34.1°C | 14.7°C | 103 mm | 74% | 2.5 m/s | 5.2 |
| 2017 | 26.6°C | 21.3°C | 16.1°C | 31.4°C | 12.3°C | 57 mm | 71% | 2.3 m/s | 5.4 |
| 2016 | 28.1°C | 23.9°C | 19.8°C | 33.3°C | 14.7°C | 185 mm | 78% | 2.1 m/s | 5.2 |
| 2015 | 26.8°C | 21.8°C | 16.7°C | 31.3°C | 11.9°C | 88 mm | 75% | 2.5 m/s | 5.3 |
| 2014 | 27.3°C | 22.7°C | 18.0°C | 29.5°C | 11.1°C | 151 mm | 77% | 2.2 m/s | 4.8 |
| 2013 | 28.1°C | 22.7°C | 17.3°C | 33.9°C | 12.3°C | 68 mm | 70% | 2.3 m/s | 5.4 |
| 2012 | 29.4°C | 23.2°C | 17.0°C | 35.7°C | 12.2°C | 99 mm | 62% | 2.2 m/s | 5.6 |
| 2011 | 27.7°C | 23.0°C | 18.2°C | 32.0°C | 14.7°C | 84 mm | 75% | 2.3 m/s | 5.7 |
| 2010 | 28.8°C | 24.1°C | 19.5°C | 32.1°C | 13.6°C | 64 mm | 77% | 2.3 m/s | 5.7 |
| 2009 | 25.8°C | 21.1°C | 16.5°C | 31.6°C | 10.4°C | 117 mm | 78% | 2.9 m/s | 5 |
| 2008 | 27.1°C | 22.0°C | 16.9°C | 30.8°C | 12.8°C | 76 mm | 74% | 2.4 m/s | 5.8 |
| 2007 🌧️ | 28.4°C | 23.8°C | 19.3°C | 33.0°C | 13.9°C | 260 mm | 79% | 2.3 m/s | 5 |
| 2006 | 27.6°C | 22.8°C | 18.0°C | 34.7°C | 12.6°C | 129 mm | 73% | 2.6 m/s | 4.8 |
| 2005 | 29.6°C | 24.3°C | 19.0°C | 34.4°C | 14.1°C | 70 mm | 67% | 2.3 m/s | 5.3 |
| 2004 | 25.4°C | 20.4°C | 15.5°C | 32.0°C | 9.3°C | 162 mm | 74% | 2.7 m/s | 5 |
| 2003 | 28.3°C | 23.0°C | 17.7°C | 34.5°C | 15.0°C | 69 mm | 73% | 2.5 m/s | 5.5 |
| 2002 | 28.9°C | 23.3°C | 17.7°C | 33.8°C | 13.9°C | 87 mm | 71% | 2.6 m/s | 5.4 |
| 2001 | 28.7°C | 23.2°C | 17.7°C | 35.7°C | 13.6°C | 135 mm | 71% | 2.5 m/s | 5.3 |
| 2000 | 28.6°C | 22.9°C | 17.2°C | 34.1°C | 11.7°C | 68 mm | 71% | 2.7 m/s | 5.6 |
| 1999 | 27.2°C | 21.8°C | 16.4°C | 32.7°C | 11.8°C | 70 mm | 69% | 2.5 m/s | 5.2 |
| 1998 | 27.7°C | 23.1°C | 18.5°C | 31.3°C | 13.7°C | 105 mm | 77% | 2.2 m/s | 5.2 |
| 1997 | 25.6°C | 20.7°C | 15.7°C | 31.9°C | 11.8°C | 125 mm | 77% | 2.6 m/s | 4.9 |
| 1996 | 26.4°C | 21.5°C | 16.5°C | 30.4°C | 13.8°C | 43 mm | 78% | 2.1 m/s | 5.6 |
| 1995 | 29.1°C | 24.6°C | 20.1°C | 32.5°C | 14.5°C | 114 mm | 81% | 1.9 m/s | 5.1 |
| 1994 | 24.9°C | 19.8°C | 14.6°C | 30.7°C | 9.1°C | 99 mm | 78% | 2.7 m/s | 4.8 |
| 1993 | 26.2°C | 22.1°C | 18.0°C | 30.6°C | 11.8°C | 142 mm | 84% | 2.3 m/s | 4.9 |
| 1992 ❄️ | 24.8°C | 19.4°C | 14.0°C | 30.4°C | 10.1°C | 57 mm | 74% | 2.7 m/s | 5.2 |
| 1991 | 28.6°C | 22.9°C | 17.2°C | 35.1°C | 14.0°C | 84 mm | 68% | 2.4 m/s | 5.5 |
| 1990 | 25.6°C | 21.0°C | 16.4°C | 29.9°C | 11.5°C | 159 mm | 81% | 2.3 m/s | 5.2 |
| 1989 | 26.8°C | 21.6°C | 16.4°C | 30.7°C | 10.6°C | 114 mm | 74% | 2.4 m/s | 5.2 |
| 1988 🔥 | 31.1°C | 25.0°C | 18.9°C | 38.2°C | 10.4°C | 96 mm | 60% | 2.7 m/s | 5.3 |
| 1987 | 26.6°C | 21.7°C | 16.8°C | 34.9°C | 10.8°C | 190 mm | 75% | 2.6 m/s | 4.7 |
| 1986 | 25.4°C | 19.8°C | 14.2°C | 30.1°C | 5.4°C | 56 mm | 69% | 2.4 m/s | 5.2 |
| 1985 | 26.1°C | 20.5°C | 15.0°C | 30.2°C | 11.1°C | 98 mm | 72% | 2.3 m/s | 4.9 |
| 1984 | 28.9°C | 22.8°C | 16.6°C | 35.1°C | 11.7°C | 44 mm | 68% | 2.4 m/s | 5.4 |
| 1983 | 29.4°C | 23.5°C | 17.6°C | 35.0°C | 12.4°C | 74 mm | 70% | 2.3 m/s | — |
| 1982 | 25.7°C | 20.2°C | 14.7°C | 30.9°C | 9.1°C | 63 mm | 72% | 2.3 m/s | — |
| 1981 | 25.8°C | 21.2°C | 16.5°C | 28.6°C | 10.9°C | 110 mm | 79% | 2.4 m/s | — |
Actual recorded August data for each year, 1981–2025 — sourced from NASA POWER.
The average high in August is around 27.6°C with lows near 17.3°C (mean 22.5°C), based on 45 years of NASA POWER data.
August averages 99 mm of rainfall in Chicago Heights, a relatively wet time of year. The wettest on record was 260 mm in 2007.
The hottest August reached 38.2°C in 1988. The coldest dipped to 5.4°C in 1986.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average August temperatures have risen by about 1.9°C. Daytime highs moved from 27.2°C to 28.9°C and overnight lows from 16.1°C to 18.1°C over the same span.
August is one of the warmer months of the year in Chicago Heights and a relatively wet time of year, so plan for around 27.6°C daytime highs and 17.3°C at night.
Not quite — August is the 11th coolest month in Chicago Heights, averaging 22.5°C.
For August in Chicago Heights, pack light layers you can adjust through the day, with typical highs of 27.6°C and lows of 17.3°C. Bring an umbrella or light rain jacket too.
Relative humidity in August averages 73% — 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 260 mm. On average, August sees 99 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 Heights 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.
