Frost dates for 78261San Antonio, TX
The average last spring frost in San Antonio is March 1 and the average first fall frost is December 1, giving a typical growing season of about 276 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Mar 1
- Average first fall frost
- Dec 1
- Growing season
- 276 days
Safer after Mar 22 (1-in-10 risk)
Possible by Nov 9 (1-in-10 risk)
First frost typically in 35 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 21 · Mar 12 · Apr 4 | Nov 1 · Nov 16 · Dec 5 | 249 days | 100% |
| Frost / freeze (32°F) | Jan 31 · Mar 1 · Mar 22 | Nov 9 · Dec 1 · Dec 26 | 276 days | 100% |
| Hard freeze (28°F) | Jan 4 · Feb 10 · Mar 9 | Nov 23 · Dec 19 · Jan 21 | 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 29 – Apr 6 |
| Tomatoes | Transplant outdoors | Mar 17 – Aug 11 |
| Peppers | Start seeds indoors | Jan 29 – Mar 1 |
| Peppers | Transplant outdoors | Mar 31 – May 1 |
| Eggplant | Start seeds indoors | Feb 15 – Mar 16 |
| Eggplant | Transplant outdoors | Mar 31 – May 1 |
| Cucumbers | Sow outdoors | Mar 31 – Aug 21 |
| Summer squash | Sow outdoors | Mar 17 – May 1 |
| Winter squash & pumpkins | Sow outdoors | Mar 31 – May 1 |
| Snap beans | Sow outdoors | Mar 17 – Sep 13 |
| Sweet corn | Sow outdoors | Mar 17 – Aug 11 |
| Watermelon & cantaloupe | Sow outdoors | Mar 31 – May 1 |
| Okra | Sow outdoors | Mar 24 – Apr 16 |
| Peas | Sow outdoors (spring) | Jan 29 – Mar 16 |
| Potatoes | Plant outdoors (spring) | Jan 29 – Mar 31 |
| Onions | Start seeds indoors (spring) | Dec 18 – Jan 14 |
| Onions | Transplant outdoors (spring) | Feb 15 – Mar 16 |
| Broccoli | Start seeds indoors (spring) | Jan 11 – Feb 14 |
| Broccoli | Transplant outdoors (spring) | Feb 15 – Mar 16 |
| Broccoli | Start seeds indoors (fall) | Aug 1 – Aug 11 |
| Broccoli | Transplant outdoors (fall) | Aug 31 – Sep 11 |
| Cabbage | Start seeds indoors (spring) | Jan 1 – Jan 29 |
| Cabbage | Transplant outdoors (spring) | Jan 29 – Mar 1 |
| Cabbage | Start seeds indoors (fall) | Jul 22 – Aug 21 |
| Cabbage | Transplant outdoors (fall) | Aug 21 – Sep 21 |
| Leaf lettuce | Sow outdoors (spring) | Jan 29 – Apr 16 |
| Leaf lettuce | Sow outdoors (fall) | Aug 21 – Oct 7 |
| Spinach | Sow outdoors (spring) | Jan 22 – Mar 7 |
| Spinach | Sow outdoors (fall) | Sep 7 – Oct 12 |
| Radishes | Sow outdoors (spring) | Jan 29 – Mar 21 |
| Radishes | Sow outdoors (fall) | Aug 21 – Oct 22 |
| Kale | Sow outdoors (spring) | Feb 15 – Mar 7 |
| Kale | Sow outdoors (fall) | Aug 14 – Sep 21 |
| Carrots | Sow outdoors (spring) | Mar 1 – Apr 16 |
| Carrots | Sow outdoors (fall) | Jul 22 – Sep 6 |
| Garlic | Plant outdoors (fall) | Nov 21 – Dec 22 |
Where these dates come from
ZIP code 78261 is matched to the NOAA station Canyon Dam, TX, 27.6 km away, at 1,000 ft elevation (89 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Canyon Dam, TX (used) | 1,000 ft | Mar 1 | Dec 1 |
| San Antonio Intl Ap, TX | 789 ft | Feb 26 | Nov 28 |
| Randolph Afb, TX | 760 ft | Feb 21 | Dec 5 |
| New Braunfels, TX | 720 ft | Mar 8 | Nov 18 |
Frost dates near San Antonio
- San Antonio, TX 78260 · last Mar 15, first Nov 13
- Bulverde, TX 78163 · last Mar 1, first Dec 1
- Schertz, TX 78154 · last Mar 8, first Nov 18
- Bergheim, TX 78004 · last Mar 15, first Nov 13
- 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
- Cibolo, TX 78108 · last Mar 8, first Nov 18
Frequently asked questions
- When is the last frost in San Antonio, TX?
- For ZIP code 78261, the average last spring frost (32°F) is March 1, based on NOAA 1991-2020 climate normals for the Canyon Dam, TX weather station. There is a 1-in-10 chance of a frost after March 22.
- When is the first frost in San Antonio, TX?
- The average first fall frost (32°F) is December 1. There is a 1-in-10 chance of frost by November 9, so tender plants are at risk from that point on.
- How long is the growing season in 78261?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 276 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.