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

Planting zone for 78255 — San Antonio, TX

ZIP code 78255 (San Antonio, Bexar County) is in USDA zone 8b: the coldest winter night averages 15 to 20 °F. The median last spring frost is March 15 and the first fall frost November 13.

Where ZIP 78255 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.

Zone8b15 to 20 °F
Coldest night−9.4 to −6.7 °C
Last frostMar 15
First frostNov 13
2012 zone8b

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 8b 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 frostMarch 15median — 50% chance of a later frost
Safe for tender plantsApril 8only 10% chance of frost after
First fall frostNovember 13median — 10% chance by Oct 31
Growing season243 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 2 and returns around November 27.

From the NOAA station Boerne, TX — 11 miles away, elevation 1,444 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 78255

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Feb 1 – Feb 15
SpinachSow outdoors · Feb 1 – Feb 22
Broccoli, cabbageStart indoors · Jan 4 – Jan 18
Broccoli, cabbageTransplant · Feb 22 – Mar 8
Onion setsPlant outdoors · Feb 15 – Mar 1
PotatoesPlant outdoors · Feb 22 – Mar 8
LettuceSow outdoors · Feb 15 – Mar 1
Carrots, beetsSow outdoors · Feb 22 – Mar 8
TomatoesStart indoors · Jan 18 – Feb 1
TomatoesTransplant · Mar 22 – Apr 5
Peppers, eggplantStart indoors · Jan 4 – Jan 18
Peppers, eggplantTransplant · Mar 29 – Apr 12
BeansSow outdoors · Mar 22 – Apr 5
Sweet cornSow outdoors · Mar 22 – Apr 5
Cucumbers, squashSow outdoors · Mar 22 – Apr 5
Fall lettuce, spinachSow outdoors · Sep 18 – Oct 2
GarlicPlant cloves · Oct 30 – Dec 4
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Mar 15) and first fall frost (Nov 13) 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 78255 came on Jan 29 — about the same time as the 1991–2020 average (Jan 27).

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 78255 is Eckrant — very cobbly clay, well drained.

TextureVery cobbly clayholds water and nutrients; slow to drain and warm up
pH7.3neutral; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter6%high
Hydrologic groupDwater soaks in very slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Eckrant-Rock outcrop association, 8 to 30 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 78255; 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 high94 °Faverage high, August
Winter low37 °Faverage low, January
Hot days95days a year at 90 °F or more
Freezing nights40nights a year at 32 °F or less
Growing degree days6,414base 50 °F — the season’s usable heat
Longest day14 h 03 mindaylight on June 21
Shortest day10 h 14 mindaylight on December 21
Onions to growShort-daysummer days stay under about 14 h 20 min, so long-day varieties won’t bulb
Precipitation38.7 inper year, rain and melted snow

Average high and low, by month

30°40°50°60°70°80°90°100°32 °FJanuary: average high 62 °F, low 37 °F 62°37° JanFebruary: average high 66 °F, low 41 °F 66°41° FebMarch: average high 72 °F, low 47 °F 72°47° MarApril: average high 79 °F, low 54 °F 79°54° AprMay: average high 84 °F, low 63 °F 84°63° MayJune: average high 90 °F, low 69 °F 90°69° JunJuly: average high 93 °F, low 71 °F 93°71° JulAugust: average high 94 °F, low 71 °F 94°71° AugSeptember: average high 89 °F, low 65 °F 89°65° SepOctober: average high 81 °F, low 56 °F 81°56° OctNovember: average high 70 °F, low 45 °F 70°45° NovDecember: average high 63 °F, low 38 °F 63°38° Dec

Precipitation by month inches

0″1″2″3″4″5″6″January: 2.03 in precipitation 2.0 JanFebruary: 2.01 in precipitation 2.0 FebMarch: 2.45 in precipitation 2.5 MarApril: 3.08 in precipitation 3.1 AprMay: 5.20 in precipitation 5.2 MayJune: 4.28 in precipitation 4.3 JunJuly: 2.62 in precipitation 2.6 JulAugust: 3.28 in precipitation 3.3 AugSeptember: 5.42 in precipitation 5.4 SepOctober: 3.60 in precipitation 3.6 OctNovember: 2.76 in precipitation 2.8 NovDecember: 1.99 in precipitation 2.0 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Boerne, TX (11 mi away); precipitation: Cross Mountain 2.1 N, TX (2 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

6 of the 8 nearest ZIP codes are in a different zone — elevation and distance from water change winter lows quickly.

782569a
San Antonio, TX · 3 mi
782579a
San Antonio, TX · 5 mi
780238b
Helotes, TX · 6 mi
782499a
San Antonio, TX · 6 mi
780158b
Boerne, TX · 7 mi
782319a
San Antonio, TX · 9 mi
782549a
San Antonio, TX · 9 mi
782409a
San Antonio, TX · 9 mi

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

Questions about 78255

What planting zone is ZIP code 78255?

ZIP code 78255 (San Antonio, TX) is in USDA hardiness zone 8b on the 2023 map: the coldest night of an average winter reaches 15 to 20 °F (−9.4 to −6.7 °C).

When is the last frost in San Antonio, TX?

The median last spring frost (32 °F) near 78255 is March 15; after April 8 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Boerne station.

When is the first frost in San Antonio, TX?

The median first fall frost near 78255 is November 13, giving a median frost-free growing season of 243 days.

When should I plant tomatoes in 78255?

Start tomato seeds indoors around Jan 18 – Feb 1 and set transplants outside around Mar 22 – Apr 5, one to three weeks after the median last frost.

How much rain and snow does 78255 get?

About 38.7 inches of precipitation a year (NOAA 1991–2020 normals, Cross Mountain 2.1 N station).

How hot do summers get in San Antonio, TX?

The average high peaks at 94 °F in August, with about 95 days a year at 90 °F or more.

What kind of soil does 78255 have?

The USDA soil survey maps Eckrant at the center of ZIP 78255: very cobbly clay, well drained, pH about 7.3 (neutral).

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

Spring leaf-out near 78255 came on Jan 29 in 2026, about the same as the 1991–2020 average (Jan 27), 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 78255 is 14 h 03 min, so summer days stay under about 14 h 20 min, so long-day varieties won’t bulb.