Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated Oct 29, 2026

Planting zone for San Antonio, TX

San Antonio, TX is in USDA zones 8b to 9a across its 82 ZIP codes. The median last spring frost is February 25 and the first fall frost November 28.

San Antonio on the zone map

Outlined: its 59 ZIP code areas · tap the map for the zone at any spot · scroll or pinch to zoom

Not the official USDA Plant Hardiness Zone Map. Zones come from the 2023 USDA hardiness-zone data by the PRISM Group, Oregon State University; we re-mapped and recolored them. The official map is at planthardiness.ars.usda.gov.

Zones8b–9a15 to 25 °F

ZIP codes82

Last frostFeb 25

First frostNov 28

Growing season277 days

8b 2 ZIPs 9a 80 ZIPs

Frost forecast — next 7 nights

live from the National Weather Service

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Forecast data: National Weather Service (api.weather.gov), public domain. This is not a warning service — for official frost and freeze warnings see weather.gov.

Frost dates in San Antonio, TX

JanFebMarAprMayJunJulAugSepOctNovDec

Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free

Last spring frostFebruary 25median — 50% chance of a later frost

Safe for tender plantsMarch 19only 10% chance of frost after

First fall frostNovember 28median — 10% chance by Nov 7

Growing season277 daysfrost-free, median

A hard freeze (28 °F) usually ends around February 5 and returns around December 15.

From the NOAA station San Antonio Incarnate Word, TX, elevation 699 ft. NOAA NCEI U.S. Climate Normals 1991–2020, 32 °F threshold. Low spots and valleys can freeze later in spring than the station.

When to plant vegetables in San Antonio

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Jan 14 – Jan 28

SpinachSow outdoors · Jan 14 – Feb 4

Broccoli, cabbageStart indoors · Dec 17 – Dec 31

Broccoli, cabbageTransplant · Feb 4 – Feb 18

Onion setsPlant outdoors · Jan 28 – Feb 11

PotatoesPlant outdoors · Feb 4 – Feb 18

LettuceSow outdoors · Jan 28 – Feb 11

Carrots, beetsSow outdoors · Feb 4 – Feb 18

TomatoesStart indoors · Dec 31 – Jan 14

TomatoesTransplant · Mar 4 – Mar 18

Peppers, eggplantStart indoors · Dec 17 – Dec 31

Peppers, eggplantTransplant · Mar 11 – Mar 25

BeansSow outdoors · Mar 4 – Mar 18

Sweet cornSow outdoors · Mar 4 – Mar 18

Cucumbers, squashSow outdoors · Mar 4 – Mar 18

Fall lettuce, spinachSow outdoors · Oct 3 – Oct 17

GarlicPlant cloves · Nov 14 – Dec 19

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Feb 25) and first fall frost (Nov 28) with the rules of thumb U.S. extension services publish. Cool-season crops take a light frost; warm-season crops do best once the soil is above about 60 °F.

When spring arrived in 2026

In 2026, spring leaf-out near 78212 came on Jan 15 — 9 days earlier than the 1991–2020 average (Jan 24).

average
Jan 242026
Jan 15

JanFebMarAprMayJun

The Spring Index marks the day when accumulated warmth is enough for lilac and honeysuckle to leaf out — a widely used signal that the growing season has started. Source: USA National Phenology Network, www.usanpn.org — Spring Indices, first leaf, 2026 (data as of 2026-09-08) and 30-year average 1991–2020 (CC BY 4.0).

Soil in San Antonio, TX

The soil mapped at the center of ZIP 78212 is Austin — silty clay, well drained.

TextureSilty clayholds water and nutrients; slow to drain and warm up

pH8.2alkaline; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter2.5%moderate

Hydrologic groupDwater soaks in very slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Austin silty clay, 2 to 5 percent slopes, moderately eroded.

Soil Survey Staff, Natural Resources Conservation Service, USDA. Soil Survey Geographic (SSURGO) Database, via Soil Data Access, accessed 2026-10-29. The soil at the center point of ZIP 78212; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in San Antonio, TX

Summer high95 °Faverage high, August

Winter low40 °Faverage low, January

Hot days112days a year at 90 °F or more

Freezing nights22nights a year at 32 °F or less

Growing degree days7,164base 50 °F — the season’s usable heat

Longest day14 h 02 mindaylight on June 21

Shortest day10 h 15 mindaylight on December 21

Onions to growShort-daysummer days stay under about 14 h 20 min, so long-day varieties won’t bulb

Precipitation34 inper year, rain and melted snow

Average high and low, by month

Precipitation by month inches

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: San Antonio Incarnate Word, TX (within 1 mile); precipitation: San Antonio Incarnate Word, TX (within 1 mile). Daylight is calculated from latitude.