Chicago weather in August 2026

Q: How hot is it in Chicago in August?

Daytime temperatures usually reach 28°C in Chicago in August with moderate heat and humidity, falling to 16°C at night.

Q: How sunny is it in Chicago in August?

There are normally 9 hours of bright sunshine each day in Chicago in August - that's 67% of daylight hours.

Q: How warm is the sea around Chicago in August?

The average sea temperature around Chicago in August is 21°C.

Q: Does it rain in Chicago in August?

There are usually 9 days with some rain in Chicago in August and the average monthly rainfall is 97mm.

Expect daytime maximum temperatures of 82°F in Chicago, Illinois in August based on long-term weather averages. There are 9 hours of sunshine per day on average with typically 3.8 inches of rainfall in the month.

82
82°F max day temperature
9
9 hours of sunshine per day
9
9 days with some rainfall
61
61°F min night temperature
14
14 hours of daylight per day
M
Moderate heat & humidity
3.8
3.8 inches of monthly rainfall
8
8 (Very High) UV index
70
70°F sea temperature

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The August weather guide for Illinois (Chicago) shows long term weather averages processed from data supplied by CRU (University of East Anglia), the Met Office & the Netherlands Meteorological Institute. Find out more about our data sources.

Metric (°C) | Imperial (°F)