San Antonio, Texas Frost Dates, Growing Season & Hardiness Zone

When is the last frost in San Antonio?

In half of years, the last 32°F night has passed by Feb 25. In 1 year out of 10, one still comes after Mar 19. The last 36°F night (frost possible on plants) typically comes later, around Mar 10, and the last 28°F hard freeze earlier, around Feb 5.

In San Antonio, late frosts can come well after the typical date. The safer 1-in-10 date (Mar 19) is 22 days after the typical date (Feb 25). Tender plants set out early will need cover on cold nights.

Cold nights don't end with the last freeze. The typical last 36°F night (frost possible on plants in low spots) comes around Mar 10, 13 days after the typical last 32°F night. On clear, calm nights, frost can form on leaves while the thermometer still reads above freezing.

Is it too early to plant in San Antonio?

Before Feb 25 the odds of another 32°F night are better than even; after Mar 19 they are about 1 in 10 or less.

Today's risk is computed in your browser from the same NOAA probability table, shown as the range between the two nearest NOAA probability levels.

When is the first frost in San Antonio?

The typical first fall freeze (32°F) comes by Nov 28, but 1 year in 10 it shows up as early as Nov 7. Cold 36°F nights (frost possible on plants) typically start around Nov 16, and the first hard freeze (28°F) typically comes around Dec 15.

For fall crops, count back from Nov 28, or from Nov 7 to be safe. Our planting calendar does the math for each crop.

How long is San Antonio's growing season?

A typical year in San Antonio has 277 days between the last spring and first fall 32°F nights. In about 1 year in 10, there are fewer than 249 days.

With a season this long, you can grow many crops twice: once in spring and again for fall.

Growing degree days measure the heat available for crops to grow. The station averages 7,164 a year (base 50°F).

How does San Antonio's season compare?

Of the 6 Texas cities with frost dates on this site, San Antonio has a typical frost-free season of 277 days, which is the 3rd longest.

Compared with the 56 U.S. cities with frost dates on this site, this typical frost-free season is longer than in 44 and shorter than in 11.

Growing degree days (base 50°F)

Annual normal: 7,164 GDD (NOAA flag R, 16 years). Running total by the end of each month (sum of NOAA daily GDD normals, so the year-end total can differ slightly from the annual normal):

What growing zone is San Antonio? (USDA 2023)

San Antonio is in USDA zone 8b–9a on the 2023 map, which means an average coldest winter night of 15 to 25°F. Most of the city was 8b on the 2012 map, and 31 of 61 city ZIPs found in both tables moved up half a zone.

Zones: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed 2026-10-08. Shown as published in the ZIP tables; this page does not show a zone map. Not the official USDA Plant Hardiness Zone Map (official map: planthardiness.ars.usda.gov).

Does the new zone change San Antonio's frost dates?

No. Zones describe only how cold the coldest winter night gets on average. They don't tell you when frost starts or stops. The frost dates for San Antonio come from NOAA's 1991–2020 frost probabilities, which the 2023 zone map left untouched. Choose winter-hardy perennials by zone, and schedule planting by frost dates.

Why do San Antonio frost dates differ between websites?

Some sources list Mar 5 for San Antonio. That's the 30%-risk date: about 3 years in 10 still see a 32°F night after it. We headline the 50% (median) date, Feb 25.

The 'safer' date, Mar 19, is the 10%-risk date. A 32°F night after it happens in only about 1 year in 10.

You may also see Mar 10. That's the 50% date for a 36°F night (frost possible on plants) rather than a 32°F freeze, so sites using 36°F as their cutoff list later dates.

The choice of weather station matters too. The 5 stations within 25 miles of the city center that pass our quality rules give typical (50%) last 32°F frost dates from Feb 18 to Feb 26; see the table below.

Which weather station is this based on?

Station

San Antonio Incarnate Word (NOAA USC00417947, COOP)

Distance

3.2 mi E of the city center

Elevation

700 ft; city center 722 ft (USGS), difference −22 ft

Record

NOAA completeness flag R, 16 of 30 years (1991–2020)

Confidence

Medium (rule)

Confidence: Medium. The station passes our quality rules, but it's farther away or at a different elevation than ideal (3.2 mi, −22 ft; NOAA flag R, 16 of 30 years).

Note: NOAA rates this station's frost statistics 'R' (representative). That means they use 16 of the 30 years in 1991–2020, with missing months filled in from surrounding stations. For comparison, the nearest station with a full 'S' (standard) record, San Antonio International Airport (6.1 mi away), has a typical last frost of Feb 26.

San Antonio planting dates at a glance

Balanced dates use the 30%-risk last-frost date as the anchor. The San Antonio planting calendar has typical and safe dates, fall planting and a month-by-month list for 26 vegetables.

When to plant tomatoes in San Antonio · Fall planting dates for San Antonio

Frost dates near San Antonio

All Texas cities

Frequently asked questions

What is the average last frost date in San Antonio?

Feb 25 is the median (50%) date for San Antonio's last 32°F night, from NOAA 1991–2020 normals at San Antonio Incarnate Word. To play it safe, use Mar 19: only about 1 year in 10 has a freeze after it.

When is the first frost in San Antonio?

Typically by Nov 28 for the first 32°F night, though about 1 year in 10 it comes as early as Nov 7. The first 36°F night (frost possible on plants) typically shows up around Nov 16.

What growing zone is San Antonio, Texas? Is San Antonio zone 8 or 9?

San Antonio is in USDA hardiness zone 8b–9a on the current 2023 map (zone 8–9 for short). On the older 2012 map, most of the city was 8b. That's why older references still say 'zone 8'.

Is it too early to plant in San Antonio?

Before Feb 25, yes, for anything frost-tender. Until then, the odds of another 32°F night are better than even. The risk falls from 50% to 10% between Feb 25 and Mar 19. Peas, lettuce and other cool-season crops can go in weeks earlier; the planting calendar has dates.

What temperature is a killing frost?

It depends on the crop. Tender plants such as tomatoes are killed by a light frost, which CSU Extension describes as 28–32°F; below 28°F is a heavy frost. We show NOAA odds for 36°F (frost possible on plants), 32°F (freeze, our headline) and 28°F (hard freeze).

Is first frost the same as first freeze?

Not quite. A freeze is when the air reaches 32°F. Frost is ice that forms on surfaces, and on calm, clear nights it can form with the air a few degrees above freezing. So in San Antonio, the first 36°F night (frost possible on plants) typically comes around Nov 16, before the first 32°F night (Nov 28).

Download & sources

• Add San Antonio frost & planting dates to your calendar (.ics, 2027)
• Printable planting calendar (PDF)
• How these numbers are calculated

Data: NOAA NCEI U.S. Climate Normals 1991–2020 (annual/seasonal and daily normals, station USC00417947); USDA Plant Hardiness Zone ZIP tables 2023 and 2012 by the PRISM Group, Oregon State University; Census 2020 ZIP/place relationship file; USGS elevation. Long-term odds, not a forecast. Figures and sentences are generated from these data by fixed rules; see the methodology. Last updated 2026-10-08.