Chicago · August
Run in the morning.
Comfortable average high of 79°F, dipping to 66°F at night. Humidity averages 77% — the limiting factor on most runs. Expect 17 rain days — plan around the radar. Humidity rises with the sun — morning runs catch the driest, coolest window.
Avg high / low
79° / 66°F
Humidity
77%
Rain days
17/mo
Wind
13 mph
What August feels like in Chicago
Sunrise
05:60
Mid-month average
Sunset
19:48
Mid-month average
Time-of-day breakdown
Morning
Coolest, driest air of the day. The window before sunrise is the most reliable comfortable hour.
Midday
Mild but UV and traffic peak. Workable if you don't mind shifting your pace.
Evening
Warm and runnable. Crowded routes but the air's typically calm.
What to wear running in Chicago in August
The kit for August in Chicago: shorts and a short-sleeve are the standard kit, a water-resistant cap or jacket on standby.
August vs the surrounding months
vs July
0° avg high
+1 rain days
Chicago in July →
August
79°F avg high
17 rain days
Best: morning
vs September
+5° avg high
+4 rain days
Chicago in September →
Frequently Asked Questions
What is the best time of day to run in Chicago in August?+
Morning. Humidity rises with the sun — morning runs catch the driest, coolest window.
What's the average temperature in Chicago in August?+
Average high 79°F, average low 66°F.
How does August compare to surrounding months in Chicago?+
Compared to July (avg high 79°F), August is cooler. Compared to September (avg high 74°F), August is warmer.
Does it rain often in Chicago in August?+
Expect about 17 measurable rain days in August, on average.