USDA Hardiness Zone 9a
Frost Dates for 78225 — San Antonio, Texas
NOAA 1991–2020 normals from San Antonio Kelly AFB, TX (682 ft), 4 miles west.
Updated
In San Antonio, the last spring frost (32°F) is around February 22 in half of years and has passed by March 12 in nine years out of ten. The first fall frost comes around December 2, as early as November 13 one year in ten, leaving a typical freeze-free season of 284 days (NOAA, San Antonio Kelly AFB, TX).
- Last spring frost
- February 22
- First fall frost
- December 2
- Growing season
- 284 days
- Hardiness zone
- 9a
50% probability
50% probability
freeze-free, 50%
20 to 25°F (-6.7 to -3.9°C) coldest night
- First snow
- Rare
- Last snow
- Rare
- Winters with snow
- 21%
- Snow per year
- 0.1"
median, 1991–2020
median, 1991–2020
4 of 19 observed
NOAA normal
Frost risk by date in San Antonio
Half of springs at San Antonio Kelly AFB, TX see their last 32°F night by February 22; only one in ten is past it by January 16, and one in ten still has one after March 12. Planting tender crops after March 2 leaves a 30% risk of a frost on them, after March 6 20%, and after March 12 10%. The 18 days between the even-odds date and the one-in-ten date is narrower than at 75% of the 339 Texas stations behind this site's ZIP pages.
In fall the first 32°F night comes by December 2 in half of years, as early as November 13 one year in ten, and holds off past December 25 one year in ten. A hard freeze of 28°F follows 14 days later, around December 16; in spring the one-in-ten date for 28°F is March 3, 9 days before the 32°F one. The freeze-free season lasts 284 days in a typical year, longer than at 80% of the 339 Texas stations; it reaches 325 days one year in ten and falls short of 255 one year in ten. On average 14 nights a year drop to 32°F or below. Nights of 36°F, when frost can still settle on leaves in low, open spots, continue 11 days longer, to about March 5, and return around November 22. Nights of 24°F, cold enough to damage hardier plants, come in 52% of winters and 16°F in 1%.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Feb 13 | Feb 22 | Feb 27 | Mar 2 | Mar 5 | Mar 9 | Mar 12 | Mar 17 | Mar 27 |
| 32°F | Jan 16 | Jan 30 | Feb 9 | Feb 17 | Feb 22 | Feb 27 | Mar 2 | Mar 6 | Mar 12 |
| 28°F91% of yrs | Dec 23 | Dec 31 | Jan 12 | Jan 23 | Feb 1 | Feb 8 | Feb 16 | Feb 24 | Mar 3 |
| 24°F52% of yrs | Dec 11 | Dec 21 | Dec 28 | Jan 1 | Jan 7 | Jan 16 | Jan 31 | Feb 11 | Feb 21 |
| 20°F14% of yrs | too rare for a date | ||||||||
| 16°F1% of yrs | too rare for a date | ||||||||
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Nov 3 | Nov 9 | Nov 13 | Nov 18 | Nov 22 | Nov 25 | Nov 29 | Dec 2 | Dec 7 |
| 32°F | Nov 13 | Nov 20 | Nov 25 | Nov 29 | Dec 2 | Dec 5 | Dec 9 | Dec 14 | Dec 25 |
| 28°F91% of yrs | Nov 25 | Dec 1 | Dec 6 | Dec 12 | Dec 16 | Dec 21 | Dec 28 | Jan 5 | Feb 1 |
| 24°F52% of yrs | Dec 5 | Dec 9 | Dec 16 | Dec 21 | Dec 27 | Jan 1 | Jan 7 | Jan 23 | Feb 10 |
| 20°F14% of yrs | too rare for a date | ||||||||
| 16°F1% of yrs | too rare for a date | ||||||||
Freeze probabilities 1991–2020 at San Antonio Kelly AFB, TX, from NOAA NCEI U.S. Climate Normals. Where a temperature is reached in fewer than 99.5% of years, the dates describe only the years that reach it. Not a forecast.
Frost risk on any date in 78225 →Compare San Antonio with another place →
Compared with the next station
The nearest other station, San Antonio Stinson Airport, TX, 5 miles southeast of San Antonio, has a last frost 2 days earlier (February 20), a first frost 1 day later (December 3), a season 7 days longer.
When it snows in San Antonio, Texas
Measurable snow is rare here: only 4 of 19 winters from 1991 to 2020 recorded 0.1 inch or more at San Antonio Incarnate Word, TX, 6.5 miles away, so there is no typical first-snow date to plan around.
Planting calendar for 78225
| When | What to do |
|---|---|
| December 14 – December 28 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| December 28 – January 11 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| January 25 – February 8 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| February 22 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by September 9 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by November 18 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| December 2 onward | Plant garlic, mulch beds, lift tender bulbsGarlic wants a cold spell; bare soil loses structure over winter. |
The weeks before and after the 50% dates are general rules of thumb, not NOAA figures; a seed packet gives the timing for each variety.
Where these figures come from
ZIP 78225 is 4 miles from San Antonio Kelly AFB, TX, which stands at 682 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 10 other ZIP codes share the station; its figures are presented in full for 78228 (San Antonio). The 2023 USDA Plant Hardiness Zone Map lists ZIP 78225 in zone 9a, the band where the coldest night of the year averaged 20 to 25°F (-6.7 to -3.9°C) over 1991–2020; a zone describes winter lows, not frost dates.
Hardiness zone and temperature range: USDA Plant Hardiness Zone Map 2023 (USDA-ARS, Oregon State University), ZIP-code listing, unchanged. °C converted from °F by this site.
Thirty-year averages, not a forecast: check the forecast before planting out. How stations are matched and which pages are offered to search engines: methodology.