Chicago weather in August
In August, Chicago has an average high of 25 °C77 °F and an average low of 20 °C68 °F, with about 105 mm4.1 in of precipitation. August is the warmest month of the year and ranks 2nd for precipitation.
How August compares with other months
Compared with July, August is about the same temperature and wetter by 10 mm0.4 in. Compared with September, August is 3.4 °C6.2 °F warmer on average and wetter by 20 mm0.8 in. Daylight lasts about 13.8 hours around the middle of the month. Average relative humidity is 77% and the average cloud amount 48%.
Is August a good time to visit Chicago?
August is not among the most comfortable months by our comfort score: it is fairly wet (105 mm4.1 in) and it is humid (77%). The most comfortable months in Chicago are June and July and September.
What to wear in August
For Chicago in August, pack light summer clothes such as T-shirts, shorts or light dresses and an umbrella or light rain jacket.
August in nearby places
| Place | High °C°F | Low °C°F | Precip. mmin |
|---|---|---|---|
| Chicago | 2577 | 2068 | 1054.1 |
| Joliet | 2883 | 1763 | 1054.1 |
| Elgin | 2883 | 1763 | 1064.2 |
| Aurora | 2883 | 1763 | 1064.2 |
| South Bend | 2883 | 1763 | 1074.2 |
| Rockford | 2781 | 1762 | 1074.2 |
| Milwaukee | 2781 | 1762 | 1003.9 |
| Madison | 2781 | 1661 | 1114.4 |
| Grand Rapids | 2780 | 1661 | 873.4 |
Nearby places that are more than 1 °C1.8 °F cooler: Madison and Grand Rapids.
Other months in Chicago
- January0 °C32 °F / −5 °C23 °F
- February0 °C33 °F / −5 °C23 °F
- March5 °C41 °F / −1 °C31 °F
- April10 °C50 °F / 4 °C39 °F
- May15 °C59 °F / 9 °C47 °F
- June21 °C70 °F / 15 °C59 °F
- July25 °C77 °F / 20 °C68 °F
- August25 °C77 °F / 20 °C68 °F
- September22 °C71 °F / 16 °C62 °F
- October15 °C59 °F / 10 °C49 °F
- November9 °C47 °F / 3 °C38 °F
- December3 °C37 °F / −2 °C29 °F
Frequently asked questions
How warm is Chicago in August?
In August the average high in Chicago is 25 °C (77 °F) and the average low is 20 °C (68 °F).
Does it rain a lot in Chicago in August?
On average about 105 mm (4.1 in) of precipitation falls in August; it ranks 2nd of the 12 months.
Is August the warmest month in Chicago?
No. The warmest month in Chicago is July, with an average high of 25 °C (77 °F). The coldest month is February, with an average low of -5 °C (23 °F).
How long is the day in Chicago in August?
In the middle of August the day in Chicago lasts about 13.8 hours from sunrise to sunset. The value is calculated from the position of the city and the sun.
How humid is Chicago in August?
The average relative humidity in August is about 77%. Combined with warm days, it can feel muggy.
How cloudy is Chicago in August?
On average about 48% of the sky is covered by cloud in August. This is the mean cloud amount from satellite data, not the number of sunny days.
About this data
All figures are 25-year averages (January 2001 – December 2025) from the NASA POWER project. Temperature, humidity, wind and precipitation come from the MERRA-2 reanalysis (precipitation is the bias-corrected MERRA-2 product), cloud and solar values from CERES satellite data. They describe a grid cell of roughly 50–70 km, not a single weather station, so they can differ from airport records — most of all on coasts, in mountains and for rainfall. Average highs and lows are the monthly mean temperature plus/minus half of the average daily temperature range. Counts of rainy days are not part of this dataset.