Frost dates for 78249San Antonio, TX
The average last spring frost in San Antonio is February 26 and the average first fall frost is November 28, giving a typical growing season of about 277 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Feb 26
- Average first fall frost
- Nov 28
- Growing season
- 277 days
Safer after Mar 17 (1-in-10 risk)
Possible by Nov 7 (1-in-10 risk)
First frost typically in 42 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) | Feb 20 · Mar 10 · Apr 2 | Nov 1 · Nov 16 · Dec 5 | 251 days | 100% |
| Frost / freeze (32°F) | Jan 29 · Feb 26 · Mar 17 | Nov 7 · Nov 28 · Dec 22 | 277 days | 100% |
| Hard freeze (28°F) | Jan 2 · Feb 9 · Mar 7 | Nov 21 · Dec 13 · Jan 19 | 311 days | 96% |
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 | Jan 26 – Apr 3 |
| Tomatoes | Transplant outdoors | Mar 14 – Aug 8 |
| Peppers | Start seeds indoors | Jan 26 – Feb 26 |
| Peppers | Transplant outdoors | Mar 28 – Apr 28 |
| Eggplant | Start seeds indoors | Feb 12 – Mar 13 |
| Eggplant | Transplant outdoors | Mar 28 – Apr 28 |
| Cucumbers | Sow outdoors | Mar 28 – Aug 18 |
| Summer squash | Sow outdoors | Mar 14 – Apr 28 |
| Winter squash & pumpkins | Sow outdoors | Mar 28 – Apr 28 |
| Snap beans | Sow outdoors | Mar 14 – Sep 10 |
| Sweet corn | Sow outdoors | Mar 14 – Aug 8 |
| Watermelon & cantaloupe | Sow outdoors | Mar 28 – Apr 28 |
| Okra | Sow outdoors | Mar 21 – Apr 13 |
| Peas | Sow outdoors (spring) | Jan 26 – Mar 13 |
| Potatoes | Plant outdoors (spring) | Jan 26 – Mar 28 |
| Onions | Start seeds indoors (spring) | Dec 15 – Jan 11 |
| Onions | Transplant outdoors (spring) | Feb 12 – Mar 13 |
| Broccoli | Start seeds indoors (spring) | Jan 8 – Feb 11 |
| Broccoli | Transplant outdoors (spring) | Feb 12 – Mar 13 |
| Broccoli | Start seeds indoors (fall) | Jul 29 – Aug 8 |
| Broccoli | Transplant outdoors (fall) | Aug 28 – Sep 8 |
| Cabbage | Start seeds indoors (spring) | Dec 29 – Jan 26 |
| Cabbage | Transplant outdoors (spring) | Jan 26 – Feb 26 |
| Cabbage | Start seeds indoors (fall) | Jul 19 – Aug 18 |
| Cabbage | Transplant outdoors (fall) | Aug 18 – Sep 18 |
| Leaf lettuce | Sow outdoors (spring) | Jan 26 – Apr 13 |
| Leaf lettuce | Sow outdoors (fall) | Aug 18 – Oct 4 |
| Spinach | Sow outdoors (spring) | Jan 19 – Mar 4 |
| Spinach | Sow outdoors (fall) | Sep 4 – Oct 9 |
| Radishes | Sow outdoors (spring) | Jan 26 – Mar 18 |
| Radishes | Sow outdoors (fall) | Aug 18 – Oct 19 |
| Kale | Sow outdoors (spring) | Feb 12 – Mar 4 |
| Kale | Sow outdoors (fall) | Aug 11 – Sep 18 |
| Carrots | Sow outdoors (spring) | Feb 26 – Apr 13 |
| Carrots | Sow outdoors (fall) | Jul 19 – Sep 3 |
| Garlic | Plant outdoors (fall) | Nov 18 – Dec 19 |
Where these dates come from
ZIP code 78249 is matched to the NOAA station San Antonio Intl Ap, TX, 12.5 km away, at 789 ft elevation (189 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| San Antonio Intl Ap, TX (used) | 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 |
| San Antonio Kelly Afb, TX | 682 ft | Feb 22 | Dec 2 |
Frost dates near San Antonio
- San Antonio, TX 78240 · last Feb 26, first Nov 28
- Helotes, TX 78023 · 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
- Boerne, TX 78015 · last Mar 15, first Nov 13
- Macdona, TX 78054 · last Feb 20, first Dec 3
- Rio Medina, TX 78066 · last Feb 28, first Nov 27
- Bulverde, TX 78163 · last Mar 1, first Dec 1
Frequently asked questions
- When is the last frost in San Antonio, TX?
- For ZIP code 78249, the average last spring frost (32°F) is February 26, based on NOAA 1991-2020 climate normals for the San Antonio Intl Ap, TX weather station. There is a 1-in-10 chance of a frost after March 17.
- When is the first frost in San Antonio, TX?
- The average first fall frost (32°F) is November 28. There is a 1-in-10 chance of frost by November 7, so tender plants are at risk from that point on.
- How long is the growing season in 78249?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 277 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.