Frost dates for 78256San Antonio, TX
The average last spring frost in San Antonio is March 15 and the average first fall frost is November 13, giving a typical growing season of about 243 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Mar 15
- Average first fall frost
- Nov 13
- Growing season
- 243 days
Safer after Apr 8 (1-in-10 risk)
Possible by Oct 31 (1-in-10 risk)
First frost typically in 13 days
Frost risk by date
NOAA reports frost dates as probabilities. The middle date is the average (a 50% chance). For spring, the 10% date is a safer planting date: frost after it happens in about 1 year in 10. Light frost (36°F) can damage tender plants; a hard freeze (28°F) kills most annuals.
| Temperature | Last spring: 90% / 50% / 10% chance | First fall: 10% / 50% / 90% chance | Growing season (50%) | Years with at least one |
|---|---|---|---|---|
| Light frost (36°F) | Mar 9 · Apr 1 · Apr 22 | Oct 21 · Nov 4 · Nov 21 | 218 days | 100% |
| Frost / freeze (32°F) | Feb 23 · Mar 15 · Apr 8 | Oct 31 · Nov 13 · Dec 4 | 243 days | 100% |
| Hard freeze (28°F) | Jan 31 · Mar 2 · Mar 23 | Nov 5 · Nov 27 · Dec 21 | 270 days | 100% |
Planting calendar for San Antonio
Planting windows from the University of Maryland Extension calendar, shifted to your average frost dates. Use them as a starting point and adjust for seed packet instructions and local conditions.
| Crop | Task | Window |
|---|---|---|
| Tomatoes | Start seeds indoors | Feb 12 – Apr 20 |
| Tomatoes | Transplant outdoors | Mar 31 – Jul 24 |
| Peppers | Start seeds indoors | Feb 12 – Mar 15 |
| Peppers | Transplant outdoors | Apr 14 – May 15 |
| Eggplant | Start seeds indoors | Mar 1 – Mar 30 |
| Eggplant | Transplant outdoors | Apr 14 – May 15 |
| Cucumbers | Sow outdoors | Apr 14 – Aug 3 |
| Summer squash | Sow outdoors | Mar 31 – May 15 |
| Winter squash & pumpkins | Sow outdoors | Apr 14 – May 15 |
| Snap beans | Sow outdoors | Mar 31 – Aug 26 |
| Sweet corn | Sow outdoors | Mar 31 – Jul 24 |
| Watermelon & cantaloupe | Sow outdoors | Apr 14 – May 15 |
| Okra | Sow outdoors | Apr 7 – Apr 30 |
| Peas | Sow outdoors (spring) | Feb 12 – Mar 30 |
| Potatoes | Plant outdoors (spring) | Feb 12 – Apr 14 |
| Onions | Start seeds indoors (spring) | Jan 1 – Jan 28 |
| Onions | Transplant outdoors (spring) | Mar 1 – Mar 30 |
| Broccoli | Start seeds indoors (spring) | Jan 25 – Feb 28 |
| Broccoli | Transplant outdoors (spring) | Mar 1 – Mar 30 |
| Broccoli | Start seeds indoors (fall) | Jul 14 – Jul 24 |
| Broccoli | Transplant outdoors (fall) | Aug 13 – Aug 24 |
| Cabbage | Start seeds indoors (spring) | Jan 15 – Feb 12 |
| Cabbage | Transplant outdoors (spring) | Feb 12 – Mar 15 |
| Cabbage | Start seeds indoors (fall) | Jul 4 – Aug 3 |
| Cabbage | Transplant outdoors (fall) | Aug 3 – Sep 3 |
| Leaf lettuce | Sow outdoors (spring) | Feb 12 – Apr 30 |
| Leaf lettuce | Sow outdoors (fall) | Aug 3 – Sep 19 |
| Spinach | Sow outdoors (spring) | Feb 5 – Mar 21 |
| Spinach | Sow outdoors (fall) | Aug 20 – Sep 24 |
| Radishes | Sow outdoors (spring) | Feb 12 – Apr 4 |
| Radishes | Sow outdoors (fall) | Aug 3 – Oct 4 |
| Kale | Sow outdoors (spring) | Mar 1 – Mar 21 |
| Kale | Sow outdoors (fall) | Jul 27 – Sep 3 |
| Carrots | Sow outdoors (spring) | Mar 15 – Apr 30 |
| Carrots | Sow outdoors (fall) | Jul 4 – Aug 19 |
| Garlic | Plant outdoors (fall) | Nov 3 – Dec 4 |
Where these dates come from
ZIP code 78256 is matched to the NOAA station Boerne, TX, 22.8 km away, at 1,445 ft elevation (123 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Boerne, TX (used) | 1,445 ft | Mar 15 | Nov 13 |
| San Antonio Intl Ap, TX | 789 ft | Feb 26 | Nov 28 |
| San Antonio/Seaworld, TX | 940 ft | Feb 18 | Dec 9 |
| San Antonio Incarnate Word, TX | 700 ft | Feb 25 | Nov 28 |
Frost dates near San Antonio
- San Antonio, TX 78257 · last Mar 15, first Nov 13
- Helotes, TX 78023 · last Mar 15, first Nov 13
- Boerne, TX 78015 · last Mar 15, first Nov 13
- Bulverde, TX 78163 · last Mar 1, first Dec 1
- Bergheim, TX 78004 · last Mar 15, first Nov 13
- Jbsa Ft Sam Houston, TX 78234 · last Feb 25, first Nov 28
- Jbsa Lackland, TX 78236 · last Feb 25, first Nov 28
- Rio Medina, TX 78066 · last Feb 28, first Nov 27
Frequently asked questions
- When is the last frost in San Antonio, TX?
- For ZIP code 78256, the average last spring frost (32°F) is March 15, based on NOAA 1991-2020 climate normals for the Boerne, TX weather station. There is a 1-in-10 chance of a frost after April 8.
- When is the first frost in San Antonio, TX?
- The average first fall frost (32°F) is November 13. There is a 1-in-10 chance of frost by October 31, so tender plants are at risk from that point on.
- How long is the growing season in 78256?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 243 days long.
- Are these frost dates a forecast?
- No. They are 30-year averages and probabilities from NOAA weather station records. Use them to plan, then watch your local forecast before planting tender crops or leaving them uncovered.