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Last and first frost dates in San Antonio

United States

In San Antonio the last spring frost usually comes around 10 February and the first autumn frost around 5 December, which leaves about 298 frost-free days (median of 2016–2025). Tomato seedlings can go into open ground from 17 February to 15 August.

Last spring frostaround 10 February
First autumn frostaround 5 December
Frost-free days298 days
Hardiness zone (USDA-equivalent)official USDA map: 9a

Median of 2016–2025 for the 25 km grid cell of the city: the last day at or below 0 °C in spring and the first in autumn (ERA5 reanalysis via Open-Meteo). In a cold year a frost can come a week or two later — Greenly warns 48 hours ahead.

When is the last frost in San Antonio?

The last frost in San Antonio usually comes around 10 February: that is the median of 2016–2025, so in about half of those years the last night at or below 0 °C came later. Hardy crops start before it and frost-tender ones only after it: in the table below arugula can go into open ground from 20 January, while corn waits until 17 February. The first autumn frost follows around 5 December, about 298 days later: harvest or cover frost-tender crops before then.

When to sow and plant

CropSow for seedlingsPlant out in a greenhouseOpen ground
Achocha18 December – 27 August27 January – 6 October17 February – 6 October
Ageratumfrom 2 December—from 17 February
Arugula——sow 20 January – 31 October
Basil31 December – 3 October7 February – 10 November28 February – 10 November
Beet——sow 20 January – 6 October
Bell Pepper9 December – 16 June7 February – 15 August28 February – 15 August
Black-eyed Susanfrom 26 November—from 17 February
Bok Choy23 December – 14 October27 January – 18 November17 February – 18 November
Borage——sow 17 February – 11 October
Broad bean——sow 20 January – 27 August
Broccoli——sow 20 January – 20 August
Brussels Sprouts15 November – 18 July30 December – 1 September20 January – 1 September
Busy Lizziefrom 25 November—from 17 February
Cabbage——sow 20 January – 28 July
Calendula——sow from 20 January
Carrot——sow 20 January – 12 September
Cauliflower18 November – 20 August30 December – 1 October20 January – 1 October
Celeriac11 November – 17 June27 January – 2 September17 February – 2 September
Celery11 November – 27 June27 January – 12 September17 February – 12 September
Celosiafrom 13 Decemberfrom 27 Januaryfrom 17 February
Chamomile——sow 20 January – 1 October
Chayote31 October – 10 June27 January – 6 September17 February – 6 September
Chickpea——sow 20 January – 17 August
Chicory5 December – 11 September—20 January – 6 October
Chili Pepper9 December – 23 July7 February – 21 September28 February – 21 September
China asterfrom 17 Decemberfrom 7 Februaryfrom 28 February
Chives——sow 20 January – 22 September
Cilantro——sow 20 January – 2 October
Corn——sow 17 February – 17 August
Corn poppy——sow from 20 January
Cosmosfrom 13 Decemberfrom 27 Januaryfrom 17 February
Cucumber10 January – 23 August7 February – 20 September28 February – 20 September
Daikon——sow 20 January – 29 September
Delphiniumfrom 1 November—from 20 January
Dill——sow 20 January – 12 October
Edging lobeliafrom 25 November—from 17 February
Eggplant9 December – 16 June7 February – 15 August28 February – 15 August
Florence fennel13 December – 27 August27 January – 11 October17 February – 11 October
Foxglovefrom 14 October—from 20 January
Garden sorrel——sow 20 January – 30 September
Green Beans——sow 17 February – 25 August
Hollyhock——sow from 20 January
Hyssop——sow 20 January – 23 August
Kale——sow 20 January – 24 September
Kiwano26 December – 30 August27 January – 1 October17 February – 1 October
Kohlrabi——sow 20 January – 4 October
Leek21 October – 8 June30 December – 17 August20 January – 17 August
Lemon balm——sow 20 January – 26 September
Lettuce——sow 20 January – 9 October
Lisianthusfrom 4 Octoberfrom 30 Decemberfrom 20 January
Lovage——sow from 20 January
Luffa27 December – 24 June7 February – 5 August28 February – 5 August
Marigoldfrom 16 Decemberfrom 27 Januaryfrom 17 February
Marjoram9 December – 11 September—28 February – 10 November
Melon10 January – 10 August7 February – 7 September28 February – 7 September
Microgreens——sow 17 February – 21 November
Moringa29 December – 16 September22 February – 10 November15 March – 10 November
Moss rosefrom 2 December—from 17 February
Mustard greens——sow 20 January – 21 October
Napa cabbage25 December – 21 September27 January – 24 October17 February – 24 October
Nasturtiumfrom 20 Decemberfrom 27 Januaryfrom 17 February
Okra27 December – 4 September7 February – 16 October28 February – 16 October
Oregano31 October – 1 September30 December – 31 October20 January – 31 October
Pansyfrom 4 Novemberfrom 30 Decemberfrom 20 January
Parsley——sow 20 January – 20 September
Parsnip——sow 20 January – 9 August
Peanut1 January – 31 July7 February – 6 September28 February – 6 September
Peas——sow 20 January – 22 September
Petuniafrom 6 Decemberfrom 7 Februaryfrom 28 February
Physalis13 December – 28 July27 January – 11 September17 February – 11 September
Pumpkin27 December – 29 June7 February – 10 August28 February – 10 August
Purple coneflowerfrom 29 October—from 20 January
Radish——sow 20 January – 5 November
Sage11 November – 28 August30 December – 16 October20 January – 16 October
Scarlet sagefrom 6 December—from 17 February
Snapdragonfrom 26 Octoberfrom 30 Decemberfrom 20 January
Soybean——sow 28 February – 16 September
Spinach——sow 20 January – 11 October
Stevia9 December – 19 July27 January – 6 September17 February – 6 September
Stock——sow from 20 January
Sunflower——sow from 17 February
Sweet alyssum——sow from 20 January
Sweet Corn5 January – 11 September27 January – 3 October17 February – 3 October
Sweet peafrom 18 Novemberfrom 30 Decemberfrom 20 January
Sweet William——sow from 20 January
Swiss Chard——sow 20 January – 6 October
Thyme——sow 20 January – 17 August
Tomato6 December – 24 June27 January – 15 August17 February – 15 August
Turnip——sow 20 January – 8 October
Watercress——sow 20 January – 19 October
Watermelon10 January – 29 July7 February – 26 August28 February – 26 August
Zinniafrom 18 Januaryfrom 22 Februaryfrom 15 March
Zucchini17 January – 28 August7 February – 18 September28 February – 18 September

Planting out: a week after the last frost once the soil is warm enough for the crop; frost-hardy crops three weeks before it; an unheated greenhouse three weeks earlier. Seedlings are sown so they are ready on that day. Each window starts on the Greenly calendar date and ends on the last day that still leaves the crop’s days to harvest (from its card) before the average first autumn frost, plus six weeks of picking for crops harvested over weeks (tomatoes, peppers, aubergines, cucumbers, courgettes, pumpkins, watermelons, beans) — our rule; earlier in the window is safer.

What planting zone is San Antonio?

The official USDA map (2023, 1991–2020 data) puts the centre of San Antonio (ZIP 78205) in zone 9a. Zone 9a stands for an average coldest night of 20 to 25 °F (-6.7 to -3.9 °C), so perennials hardy to zone 9a or a colder zone should come through a typical winter here.

Check the official USDA map for San Antonio: USDA Plant Hardiness Zone Map.

When the soil warms up in San Antonio

The day the top 7 cm of soil first averages each temperature over a week, median of 2016–2025 (ERA5 via Open-Meteo).

SoilDateAgainst the last spring frost
5 °Calready in the first week of January—
10 °Calready in the first week of January—
15 °C5 February5 days earlier
18 °C28 February18 days later

Frost dates near San Antonio

Of the nearest cities on our list, the last spring frost ends earliest in Reynosa (22 January) and latest in Austin (19 February).

CityDistanceLast spring frostFirst autumn frost
Austin119 km19 February13 December
Corpus Christi215 km27 January23 December
Nuevo Laredo238 km27 January23 December
Houston304 km17 February27 November
Reynosa371 km22 January23 December

Seeds, seedlings and markets in San Antonio

Within 15 km of San Antonio OpenStreetMap lists 3 garden centres, 4 markets and 1 farm shop (collected 20 October 2026). The nearest garden centre to the city centre is San Antonio Garden Center, 5 km away.

Places: © OpenStreetMap contributors, ODbL.

What to grow at home in winter in San Antonio

Frosts in San Antonio usually come from about 5 December to about 10 February. These plants have indoor care in their Greenly cards and are harvested quickly, so they can be sown on a windowsill in winter.

Weather in San Antonio by month

Average weather in San Antonio over 2016–2025: the warmest month is August. Months that average 20 °C or more by day: February–November (20.4–35.5 °C). Months that average 30 °C or more by day: May–September (30.7–35.5 °C). No month averages below 0 °C at night; the coldest nights, in January, average 6.8 °C. About 1002 mm of rain falls in a year, on 117 days; May is the wettest month (167 mm) and January the driest (53 mm).

MonthDay, °CNight, °CRain, mmRainy days
January17.66.8537
February20.48.8598
March25.213.56511
April27.816.39412
May30.720.116716
June3423.28012
July35.124.3858
August35.524.7889
September32.422.41079
October28.517.7808
November22.412.5679
December19.39.3578

Average of the daily highs and lows, rain per month and days with at least 1 mm (ERA5 via Open-Meteo, the same grid cell as the frost dates).

Planted in autumn

CropWhen to plant
Bearded Irisby 5 November
Crocusby 5 November
Daffodilby 5 November
Garlicby 5 November
Grape hyacinthby 5 November
Helleboreby 5 November
Hyacinthby 5 November
Lilyby 5 November
Ornamental onionby 5 November
Peonyby 5 November
Saffronby 5 November
Snowdropby 5 November
Tulipby 5 November
Wild garlicby 5 November

From a month before the first autumn frost, so the roots grow before winter, to the late-planting limit on each crop’s page (about two weeks before the ground freezes, by ten years of weather).