San Antonio, Texas weather in September

Averages from 2021–2025 (150 days of record).

Average high: 93°F
Average low: 73°F
Rainy days: ~6 per month
Total precipitation: 1.6 in
Warmest recorded: 102°F
Coldest recorded: 61°F

Expect September days in San Antonio, Texas to top out around 93°F and cool to about 73°F overnight, with roughly 6 days of measurable rain across the month. In recent years September has ranged from 61°F to 102°F.

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Current San Antonio, Texas forecast → · Historical data by Open-Meteo (ERA5).