Frost dates for 78266San Antonio, TX
The average last spring frost in San Antonio is March 8 and the average first fall frost is November 18, giving a typical growing season of about 253 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Mar 8
- Average first fall frost
- Nov 18
- Growing season
- 253 days
Safer after Apr 1 (1-in-10 risk)
Possible by Nov 2 (1-in-10 risk)
First frost typically in 16 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 28 · Mar 25 · Apr 18 | Oct 25 · Nov 7 · Nov 25 | 227 days | 100% |
| Frost / freeze (32°F) | Feb 17 · Mar 8 · Apr 1 | Nov 2 · Nov 18 · Dec 10 | 253 days | 100% |
| Hard freeze (28°F) | Jan 29 · Feb 24 · Mar 17 | Nov 10 · Dec 2 · Jan 8 | 284 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 5 – Apr 13 |
| Tomatoes | Transplant outdoors | Mar 24 – Jul 29 |
| Peppers | Start seeds indoors | Feb 5 – Mar 8 |
| Peppers | Transplant outdoors | Apr 7 – May 8 |
| Eggplant | Start seeds indoors | Feb 22 – Mar 23 |
| Eggplant | Transplant outdoors | Apr 7 – May 8 |
| Cucumbers | Sow outdoors | Apr 7 – Aug 8 |
| Summer squash | Sow outdoors | Mar 24 – May 8 |
| Winter squash & pumpkins | Sow outdoors | Apr 7 – May 8 |
| Snap beans | Sow outdoors | Mar 24 – Aug 31 |
| Sweet corn | Sow outdoors | Mar 24 – Jul 29 |
| Watermelon & cantaloupe | Sow outdoors | Apr 7 – May 8 |
| Okra | Sow outdoors | Mar 31 – Apr 23 |
| Peas | Sow outdoors (spring) | Feb 5 – Mar 23 |
| Potatoes | Plant outdoors (spring) | Feb 5 – Apr 7 |
| Onions | Start seeds indoors (spring) | Dec 25 – Jan 21 |
| Onions | Transplant outdoors (spring) | Feb 22 – Mar 23 |
| Broccoli | Start seeds indoors (spring) | Jan 18 – Feb 21 |
| Broccoli | Transplant outdoors (spring) | Feb 22 – Mar 23 |
| Broccoli | Start seeds indoors (fall) | Jul 19 – Jul 29 |
| Broccoli | Transplant outdoors (fall) | Aug 18 – Aug 29 |
| Cabbage | Start seeds indoors (spring) | Jan 8 – Feb 5 |
| Cabbage | Transplant outdoors (spring) | Feb 5 – Mar 8 |
| Cabbage | Start seeds indoors (fall) | Jul 9 – Aug 8 |
| Cabbage | Transplant outdoors (fall) | Aug 8 – Sep 8 |
| Leaf lettuce | Sow outdoors (spring) | Feb 5 – Apr 23 |
| Leaf lettuce | Sow outdoors (fall) | Aug 8 – Sep 24 |
| Spinach | Sow outdoors (spring) | Jan 29 – Mar 14 |
| Spinach | Sow outdoors (fall) | Aug 25 – Sep 29 |
| Radishes | Sow outdoors (spring) | Feb 5 – Mar 28 |
| Radishes | Sow outdoors (fall) | Aug 8 – Oct 9 |
| Kale | Sow outdoors (spring) | Feb 22 – Mar 14 |
| Kale | Sow outdoors (fall) | Aug 1 – Sep 8 |
| Carrots | Sow outdoors (spring) | Mar 8 – Apr 23 |
| Carrots | Sow outdoors (fall) | Jul 9 – Aug 24 |
| Garlic | Plant outdoors (fall) | Nov 8 – Dec 9 |
Where these dates come from
ZIP code 78266 is matched to the NOAA station New Braunfels, TX, 14.3 km away, at 720 ft elevation (202 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| New Braunfels, TX (used) | 720 ft | Mar 8 | Nov 18 |
| Randolph Afb, TX | 760 ft | Feb 21 | Dec 5 |
| San Antonio Intl Ap, TX | 789 ft | Feb 26 | Nov 28 |
| Canyon Dam, TX | 1,000 ft | Mar 1 | Dec 1 |
Frost dates near San Antonio
- Schertz, TX 78154 · last Mar 8, first Nov 18
- San Antonio, TX 78261 · last Mar 1, first Dec 1
- Cibolo, TX 78108 · last Mar 8, first Nov 18
- Universal City, TX 78148 · last Feb 21, first Dec 5
- New Braunfels, TX 78132 · last Mar 1, first Dec 1
- Converse, TX 78109 · last Feb 25, first Nov 28
- Marion, TX 78124 · last Mar 8, first Nov 18
- Bulverde, TX 78163 · last Mar 1, first Dec 1
Frequently asked questions
- When is the last frost in San Antonio, TX?
- For ZIP code 78266, the average last spring frost (32°F) is March 8, based on NOAA 1991-2020 climate normals for the New Braunfels, TX weather station. There is a 1-in-10 chance of a frost after April 1.
- When is the first frost in San Antonio, TX?
- The average first fall frost (32°F) is November 18. There is a 1-in-10 chance of frost by November 2, so tender plants are at risk from that point on.
- How long is the growing season in 78266?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 253 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.