St Louis, Missouri weather in August

Averages from 2021–2025 (155 days of record).

Average high: 86°F
Average low: 69°F
Rainy days: ~10 per month
Total precipitation: 3.5 in
Warmest recorded: 100°F
Coldest recorded: 55°F

Expect August days in St Louis, Missouri to top out around 86°F and cool to about 69°F overnight, with roughly 10 days of measurable rain across the month. In recent years August has ranged from 55°F to 100°F.

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Current St Louis, Missouri forecast → · Historical data by Open-Meteo (ERA5).