Climate & Weather in San Antonio
San Antonio has a humid subtropical climate with long, genuinely hot summers and mild winters. Summer daytime highs commonly reach the mid-90s°F and above, with an average of about 18 days a year hitting 100°F or higher, concentrated in July through September -- a real, physically demanding stretch of heat, not a mild Sun Belt exaggeration.
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Learn moreSummer: Long and Genuinely Hot
San Antonio's summer average temperature runs around 86°F, with August daytime highs commonly reaching about 97°F (36°C) and overnight lows staying above roughly 69-79°F most nights, per aggregated NOAA-sourced climate data reviewed August 2026. The city averages about 18 days a year at 100°F or higher -- a real, sourced figure worth taking seriously when planning a summer move or outdoor activity, not just a generic "hot Texas summer" characterization.
Winter: Mild, With Occasional Cold Snaps
Winters in San Antonio are mild by most national standards -- nothing resembling a true four-season winter -- though the region, like much of Texas, is not immune to occasional severe cold-snap events (Texas's February 2021 statewide winter storm is the best-known recent example of how far outside the normal range an occasional cold event can push). Treat "mild winters" as the norm, not an absolute guarantee against any winter weather risk.
Humidity
San Antonio's humid subtropical classification means humidity is a real, year-round factor rather than a summer-only nuisance, though it's less extreme and less consistently present than in coastal Gulf cities like Tampa or Houston -- the Hill Country terrain and greater distance from the coast give San Antonio somewhat drier air on average than Texas's coastal metros, even though it is not a dry climate the way West Texas or El Paso are.
What This Means Day to Day
The combination of long, hot summers and San Antonio's flash-flood-prone rainfall pattern (see the flood-hurricane-risk topic page) means both heat and sudden intense rain are normal, planned-around features of life here -- residents commonly structure outdoor activity around early mornings in summer and stay alert to flash-flood warnings during intense rain events, rather than treating either as a rare occurrence.
Key takeaways
- Humid subtropical climate: summer average around 86°F, August highs near 97°F, with about 18 days/year at 100°F or higher (concentrated July-September).
- Winters are mild by national standards, though Texas is not immune to occasional severe cold-snap events (e.g., February 2021) -- mild is the norm, not a guarantee.
- Humidity is a year-round factor but somewhat less extreme than Texas's Gulf Coast cities, given San Antonio's inland Hill Country location.
- Both summer heat and sudden intense rainfall (tied to the region's flash-flood risk) are normal, planned-around features of daily life here.
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