San Antonio, TX Frost Dates: Last Spring and First Fall Frost

Frost leaves San Antonio on February 25 and comes back on November 28 when the odds are even, a window of 277 days for tender plants.

Even odds are a coin toss, so plan around the safer edges: one spring in ten still has a freeze on or after March 19, and one fall in ten has its first freeze by November 7. Compared with the 100-city median of 229 days, San Antonio gets 48 days extra before frost returns.

NOAA measured them at San Antonio Incarnate Word (station USC00417947), about 3.2 miles east of the Census Bureau's internal point for San Antonio and about 700 feet above sea level.

When is the last frost in San Antonio?

One year in ten has a freeze on or after March 19. In nine years out of ten there is still a freeze on or after January 28, and half of years see one on or after February 25.

The earliest and latest of these dates are 50 days apart, wider than for most of the 100 cities here. A freeze can still come 22 days after the typical date in San Antonio, which is why the late date matters more here than in most places.

San Antonio's first fall frost, by chance

NOAA's early fall date for San Antonio is November 7, its even-odds date is November 28 and its late date is December 21; the first freeze has come by each of them in one, five and nine years out of ten.

44 days separate the early and late fall dates, a broad band compared with most cities here, so a fall crop in San Antonio should be planned against the early date, not the typical one.

San Antonio's frost-free season

That is longer than most places on these pages, though not by enough to change which crops you can grow. The gap between a typical year and a short one is 28 days, wider than for most cities on these pages. Count on 249 days, not 277 days, when a crop has little slack.

NOAA counts these days from its own simulations, so they will not equal the number of days between the two typical dates exactly. At San Antonio Incarnate Word a night at or below 32°F turns up in 100% of years, which means these dates apply every winter.

When a hard freeze reaches San Antonio

A wide gap separates 32°F from 28°F here: the typical hard freeze arrives 17 days after the first frost in fall (December 15) and leaves 20 days before the last in spring (February 5). Frost-tolerant crops get a long extension at both ends. One spring in ten still has a 28°F night on or after March 5, and one fall in ten sees the first by November 19.

Using San Antonio's frost dates in the garden

Counting from February 25, University of New Hampshire Extension puts cabbage transplants out on January 28 and lettuce from January 28 to February 4, ahead of the last frost, and holds peppers until March 11 and beans until February 25 or later. Peas have no frost-based date in the University of New Hampshire Extension sheet: they go in as soon as the soil thaws.

From the late date, March 19, every tender crop moves back 22 days; that buys protection against a spring only one year in ten brings.

Of the 34 crops in the fall planner, 32 still have a July-or-later last planting day in San Antonio once NC State Extension's days to harvest and University of Georgia Extension's harvest allowance of 18 days are counted back from frost. The other 2 do not. The slowest crop that still fits is collard greens, which needs 118 days before the early first frost and so must be in by July 12.

Worked example: planting broccoli for fall in San Antonio

Broccoli transplants need up to 80 days to reach harvest by NC State Extension's table, and University of Georgia Extension adds 18 days to harvest, so 98 days must pass before frost. In San Antonio the last planting day is August 22 against the typical first frost on November 28, and August 1 against the early date on November 7.

21 days separate the two last days, enough that in San Antonio the earlier one is worth following.

The same crop family has a spring clock too. University of New Hampshire Extension sets cabbage out ahead of the last frost, and from February 25 in San Antonio that means on January 28.

Where San Antonio's numbers are measured

3.2 miles east of the city's internal point, the station is close but not on top of San Antonio.

NOAA lists it at about 700 feet, higher than 53 and lower than 45 of the 100 stations in this set. NOAA flags this station's record as representative, the code R, for the data behind its 50% last-frost value.

The Census Gazetteer gives no elevation for San Antonio itself, so this page cannot tell you whether your garden sits above or below the station. If it is noticeably higher or lower, compare the stations the frost dates tool lists nearby and lean toward the colder reading.

How San Antonio's frost dates compare

The nearest city on these pages is Austin, TX, 74 miles away, and the other two below are farther out, so these are regional comparisons, not neighbors.

• Austin, TX lies 74 miles north-east of San Antonio. Typical last frost February 20, first frost December 3, 291 days between; spring frost ends 5 days sooner than in San Antonio, and the season runs 14 days longer.
• Laredo, TX, 144 miles to the south-west: last frost January 25, first frost December 17, 329 days frost-free; its last frost comes 31 days before San Antonio's, and it has 52 days more without frost.
• Houston, TX (190 miles, east): spring frost ends 23 days sooner than in San Antonio, and the frost-free season is 50 days longer than San Antonio's. Its typical dates are February 2 and December 25, with 327 days frost-free.

Put the frost dates to work

To go beyond the crops above, use the spring planting planner and fall planting planner, both set to this station. The frost dates tool shows the full odds for San Antonio, and the hardiness zone lookup gives the winter-cold zone for your ZIP code.

Looking for another city? The city frost dates index lists every page, grouped by state.

For Texas, the state planting pages copy the Extension calendar (Texas A&M AgriLife Extension) crop by crop and region by region: tomatoes in Texas, peppers in Texas, cucumbers in Texas, summer squash in Texas, green beans in Texas. Set those windows beside the frost dates above.

Where these numbers come from

NOAA's U.S. Climate Normals for 1991–2020 (doi:10.25921/4ek7-fk11) supply every frost date here, unchanged from the station's record, and NOAA's documentation defines the probabilities. The Census Bureau's 2024 Gazetteer places San Antonio on the map, and its Vintage 2024 estimates, 1,526,656 people here, decide which cities get a page.

Planting dates here are those rules from University of New Hampshire Extension, NC State Extension and University of Georgia Extension, applied to this station's frost dates and nothing else. Our methodology describes the tests behind every number.

NOAA's dates say how often frost has come, not when it will. Check the forecast before planting and keep a cover on hand.