St. Louis · August
Run in the pre-dawn.
Average high is 85°F with a 69°F overnight low. Expect 16 rain days — plan around the radar. Humid heat punishes mid-morning — get out before sunrise for the only truly comfortable window.
Avg high / low
85° / 69°F
Humidity
74%
Rain days
16/mo
Wind
9 mph
What August feels like in St. Louis
Sunrise
06:16
Mid-month average
Sunset
19:53
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
Heat peaks here. Skip unless you've got shade and pace tolerance.
Evening
Cools off after sunset but still warm. Good for easy efforts; avoid hard intervals if you're chasing pace.
What to wear running in St. Louis in August
The kit for August in St. Louis: light, breathable, and moisture-wicking — singlet or short-sleeve only, a water-resistant cap or jacket on standby.
August vs the surrounding months
vs July
-2° avg high
0 rain days
St. Louis in July →
August
85°F avg high
16 rain days
Best: pre-dawn
vs September
+4° avg high
+5 rain days
St. Louis in September →
Frequently Asked Questions
What is the best time of day to run in St. Louis in August?+
Pre-dawn. Humid heat punishes mid-morning — get out before sunrise for the only truly comfortable window.
What's the average temperature in St. Louis in August?+
Average high 85°F, average low 69°F.
How does August compare to surrounding months in St. Louis?+
Compared to July (avg high 88°F), August is cooler. Compared to September (avg high 81°F), August is warmer.
Does it rain often in St. Louis in August?+
Expect about 16 measurable rain days in August, on average.