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

Planting zone for 78245 — San Antonio, TX

ZIP code 78245 (San Antonio, Bexar County) is in USDA zone 9a: the coldest winter night averages 20 to 25 °F. The median last spring frost is February 18 and the first fall frost December 9.

Where ZIP 78245 is

Outlined: the ZIP code area · 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.

Zone9a20 to 25 °F
Coldest night−6.7 to −3.9 °C
Last frostFeb 18
First frostDec 9
2012 zone9a

Same zone as on the 2012 map. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 9a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for San Antonio, TX…

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 18median — 50% chance of a later frost
Safe for tender plantsMarch 16only 10% chance of frost after
First fall frostDecember 9median — 10% chance by Nov 17
Growing season296 daysfrost-free, median

A hard freeze (28 °F) usually ends around January 31 and returns around December 29.

From the NOAA station San Antonio/Seaworld, TX — 4 miles away, elevation 942 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 78245

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Jan 7 – Jan 21
SpinachSow outdoors · Jan 7 – Jan 28
Broccoli, cabbageStart indoors · Dec 10 – Dec 24
Broccoli, cabbageTransplant · Jan 28 – Feb 11
Onion setsPlant outdoors · Jan 21 – Feb 4
PotatoesPlant outdoors · Jan 28 – Feb 11
LettuceSow outdoors · Jan 21 – Feb 4
Carrots, beetsSow outdoors · Jan 28 – Feb 11
TomatoesStart indoors · Dec 24 – Jan 7
TomatoesTransplant · Feb 25 – Mar 11
Peppers, eggplantStart indoors · Dec 10 – Dec 24
Peppers, eggplantTransplant · Mar 4 – Mar 18
BeansSow outdoors · Feb 25 – Mar 11
Sweet cornSow outdoors · Feb 25 – Mar 11
Cucumbers, squashSow outdoors · Feb 25 – Mar 11
Fall lettuce, spinachSow outdoors · Oct 14 – Oct 28
GarlicPlant cloves · Nov 25 – Dec 30
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Feb 18) and first fall frost (Dec 9) 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 78245 came on Jan 29 — 5 days later than the 1991–2020 average (Jan 24).

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).

Native plants for zone 9a in Texas

640 plants native to the lower 48 states, recorded in Texas, and rated by the USDA to survive 20 °F or colder — the bottom of zone 9a. Each links to its USDA PLANTS profile.

Trees 72

American basswood100 ft · blooms late spring · low shade tolerance · to −46 °FAmerican beech80 ft · blooms mid spring · low shade tolerance · to −44 °FAmerican elm120 ft · blooms early spring · medium shade tolerance · to −46 °FAmerican sycamore100 ft · blooms spring · medium shade tolerance · to −34 °FArizona cypress50 ft · blooms spring · low shade tolerance · to −23 °FArizona walnut50 ft · blooms late spring · high shade tolerance · to −33 °F

Shrubs 141

alderleaf mountain mahogany15 ft · blooms late spring · medium shade tolerance · to −41 °Faloe yucca15 ft · blooms early summer · medium shade tolerance · to −1 °FAmerican beautyberry6 ft · blooms early summer · medium shade tolerance · to −8 °FAmerican holly40 ft · blooms mid spring · low shade tolerance · to −20 °FAmerican hornbeam30 ft · blooms mid spring · low shade tolerance · to −34 °FAmerican snowbell10 ft · blooms spring · medium shade tolerance · to −16 °F

Wildflowers & perennials 208

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °Falpine mountainsorrel1 ft · blooms mid summer · medium shade tolerance · to −43 °FAmerican bur-reed3 ft · blooms indeterminate · medium shade tolerance · to −33 °FAmerican century plant6 ft · blooms indeterminate · high shade tolerance · to 12 °FAmerican eelgrass1 ft · blooms mid summer · high shade tolerance · to −33 °FAmerican licorice4 ft · blooms late spring · medium shade tolerance · to −38 °F

Grasses 196

alkali sacaton3 ft · blooms mid summer · high shade tolerance · to −38 °FAmerican cupscale3 ft · blooms early summer · high shade tolerance · to −18 °FArizona cottontop4 ft · blooms late summer · high shade tolerance · to −13 °FArizona fescue2 ft · blooms late spring · high shade tolerance · to −23 °FArizona threeawn2 ft · blooms mid summer · high shade tolerance · to −3 °Fautumn bluegrass1.5 ft · blooms late spring · medium shade tolerance · to −8 °F

Vines 14

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °FAmerican wisteria50 ft · blooms spring · low shade tolerance · to −3 °Fcatbird grape30 ft · blooms late spring · medium shade tolerance · to −13 °Fcupseed30 ft · blooms late spring · low shade tolerance · to −3 °Fdevil's darning needles15 ft · blooms mid summer · medium shade tolerance · to −38 °Ffrost grape83 ft · blooms late spring · medium shade tolerance · to −23 °F

Source: USDA, NRCS. 2026. The PLANTS Database (plants.usda.gov), National Plant Data Team — state distribution, native status and the “Temperature, Minimum” characteristic. Check light, moisture and soil needs before buying; local nurseries and your state native plant society can confirm what thrives in San Antonio, TX.

Soil in San Antonio, TX

The soil mapped at the center of ZIP 78245 is Olmos — very cobbly loam, well drained.

TextureVery cobbly loama good balance for most vegetables
pH8.2alkaline; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter1%low — add compost
Hydrologic groupDwater soaks in very slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Rock outcrop-Olmos complex, 5 to 25 percent slopes.

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 78245; 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 high99 °Faverage high, August
Winter low43 °Faverage low, January
Hot days123days a year at 90 °F or more
Freezing nights14nights a year at 32 °F or less
Growing degree days7,892base 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
Precipitation34.3 inper year, rain and melted snow

Average high and low, by month

30°40°50°60°70°80°90°100°110°32 °FJanuary: average high 65 °F, low 43 °F 65°43° JanFebruary: average high 70 °F, low 46 °F 70°46° FebMarch: average high 76 °F, low 53 °F 76°53° MarApril: average high 83 °F, low 60 °F 83°60° AprMay: average high 89 °F, low 67 °F 89°67° MayJune: average high 95 °F, low 73 °F 95°73° JunJuly: average high 97 °F, low 74 °F 97°74° JulAugust: average high 99 °F, low 74 °F 99°74° AugSeptember: average high 93 °F, low 70 °F 93°70° SepOctober: average high 85 °F, low 62 °F 85°62° OctNovember: average high 74 °F, low 51 °F 74°51° NovDecember: average high 66 °F, low 44 °F 66°44° Dec

Precipitation by month inches

0″1″2″3″4″5″January: 1.96 in precipitation 2.0 JanFebruary: 1.81 in precipitation 1.8 FebMarch: 2.23 in precipitation 2.2 MarApril: 2.50 in precipitation 2.5 AprMay: 4.74 in precipitation 4.7 MayJune: 3.76 in precipitation 3.8 JunJuly: 2.61 in precipitation 2.6 JulAugust: 3.21 in precipitation 3.2 AugSeptember: 3.65 in precipitation 3.6 SepOctober: 3.56 in precipitation 3.6 OctNovember: 2.43 in precipitation 2.4 NovDecember: 1.86 in precipitation 1.9 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: San Antonio/Seaworld, TX (4 mi away); precipitation: Castroville 7.0 Ne, TX (4 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 9a.

782529a
San Antonio, TX · 5 mi
780549a
Macdona, TX · 6 mi
782539a
San Antonio, TX · 6 mi
782519a
San Antonio, TX · 6 mi
782279a
San Antonio, TX · 6 mi
782369a
Jbsa Lackland, TX · 7 mi
780029a
Atascosa, TX · 8 mi
780399a
La Coste, TX · 8 mi

All 82 ZIP codes in San Antonio → · Texas planting zones →

Questions about 78245

What planting zone is ZIP code 78245?

ZIP code 78245 (San Antonio, TX) is in USDA hardiness zone 9a on the 2023 map: the coldest night of an average winter reaches 20 to 25 °F (−6.7 to −3.9 °C).

When is the last frost in San Antonio, TX?

The median last spring frost (32 °F) near 78245 is February 18; after March 16 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, San Antonio/Seaworld station.

When is the first frost in San Antonio, TX?

The median first fall frost near 78245 is December 9, giving a median frost-free growing season of 296 days.

When should I plant tomatoes in 78245?

Start tomato seeds indoors around Dec 24 – Jan 7 and set transplants outside around Feb 25 – Mar 11, one to three weeks after the median last frost.

How much rain and snow does 78245 get?

About 34.3 inches of precipitation a year (NOAA 1991–2020 normals, Castroville 7.0 Ne station).

How hot do summers get in San Antonio, TX?

The average high peaks at 99 °F in August, with about 123 days a year at 90 °F or more.

What kind of soil does 78245 have?

The USDA soil survey maps Olmos at the center of ZIP 78245: very cobbly loam, well drained, pH about 8.2 (alkaline).

Did spring come early in San Antonio, TX in 2026?

Spring leaf-out near 78245 came on Jan 29 in 2026, 5 days later than the 1991–2020 average (Jan 24), according to the USA National Phenology Network Spring Index.

What kind of onions grow in San Antonio, TX?

Short-day onions: the longest day near 78245 is 14 h 02 min, so summer days stay under about 14 h 20 min, so long-day varieties won’t bulb.