Frost dates for 78254San Antonio, TX
The average last spring frost in San Antonio is February 18 and the average first fall frost is December 9, giving a typical growing season of about 296 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Feb 18
- Average first fall frost
- Dec 9
- Growing season
- 296 days
Safer after Mar 16 (1-in-10 risk)
Possible by Nov 17 (1-in-10 risk)
First frost typically in 43 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 11 · Mar 4 · Mar 31 | Nov 5 · Nov 25 · Dec 15 | 264 days | 100% |
| Frost / freeze (32°F) | Jan 18 · Feb 18 · Mar 16 | Nov 17 · Dec 9 · Jan 13 | 296 days | 99% |
| Hard freeze (28°F) | Dec 17 · Jan 31 · Mar 3 | Nov 28 · Dec 29 · Feb 9 | 334 days | 79% |
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 18 – Mar 26 |
| Tomatoes | Transplant outdoors | Mar 6 – Aug 19 |
| Peppers | Start seeds indoors | Jan 18 – Feb 18 |
| Peppers | Transplant outdoors | Mar 20 – Apr 20 |
| Eggplant | Start seeds indoors | Feb 4 – Mar 5 |
| Eggplant | Transplant outdoors | Mar 20 – Apr 20 |
| Cucumbers | Sow outdoors | Mar 20 – Aug 29 |
| Summer squash | Sow outdoors | Mar 6 – Apr 20 |
| Winter squash & pumpkins | Sow outdoors | Mar 20 – Apr 20 |
| Snap beans | Sow outdoors | Mar 6 – Sep 21 |
| Sweet corn | Sow outdoors | Mar 6 – Aug 19 |
| Watermelon & cantaloupe | Sow outdoors | Mar 20 – Apr 20 |
| Okra | Sow outdoors | Mar 13 – Apr 5 |
| Peas | Sow outdoors (spring) | Jan 18 – Mar 5 |
| Potatoes | Plant outdoors (spring) | Jan 18 – Mar 20 |
| Onions | Start seeds indoors (spring) | Dec 7 – Jan 3 |
| Onions | Transplant outdoors (spring) | Feb 4 – Mar 5 |
| Broccoli | Start seeds indoors (spring) | Dec 31 – Feb 3 |
| Broccoli | Transplant outdoors (spring) | Feb 4 – Mar 5 |
| Broccoli | Start seeds indoors (fall) | Aug 9 – Aug 19 |
| Broccoli | Transplant outdoors (fall) | Sep 8 – Sep 19 |
| Cabbage | Start seeds indoors (spring) | Dec 21 – Jan 18 |
| Cabbage | Transplant outdoors (spring) | Jan 18 – Feb 18 |
| Cabbage | Start seeds indoors (fall) | Jul 30 – Aug 29 |
| Cabbage | Transplant outdoors (fall) | Aug 29 – Sep 29 |
| Leaf lettuce | Sow outdoors (spring) | Jan 18 – Apr 5 |
| Leaf lettuce | Sow outdoors (fall) | Aug 29 – Oct 15 |
| Spinach | Sow outdoors (spring) | Jan 11 – Feb 24 |
| Spinach | Sow outdoors (fall) | Sep 15 – Oct 20 |
| Radishes | Sow outdoors (spring) | Jan 18 – Mar 10 |
| Radishes | Sow outdoors (fall) | Aug 29 – Oct 30 |
| Kale | Sow outdoors (spring) | Feb 4 – Feb 24 |
| Kale | Sow outdoors (fall) | Aug 22 – Sep 29 |
| Carrots | Sow outdoors (spring) | Feb 18 – Apr 5 |
| Carrots | Sow outdoors (fall) | Jul 30 – Sep 14 |
| Garlic | Plant outdoors (fall) | Nov 29 – Dec 30 |
Where these dates come from
ZIP code 78254 is matched to the NOAA station San Antonio/Seaworld, TX, 12.3 km away, at 940 ft elevation (172 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| San Antonio/Seaworld, TX (used) | 940 ft | Feb 18 | Dec 9 |
| San Antonio Kelly Afb, TX | 682 ft | Feb 22 | Dec 2 |
| San Antonio Intl Ap, TX | 789 ft | Feb 26 | Nov 28 |
| Boerne, TX | 1,445 ft | Mar 15 | Nov 13 |
Frost dates near San Antonio
- Helotes, TX 78023 · last Mar 15, first Nov 13
- San Antonio, TX 78250 · last Feb 26, first Nov 28
- Rio Medina, TX 78066 · last Feb 28, first Nov 27
- Mico, TX 78056 · last Mar 6, first Nov 20
- Boerne, TX 78015 · last Mar 15, first Nov 13
- Pipe Creek, TX 78063 · last Mar 15, first Nov 13
- Castroville, TX 78009 · last Feb 28, first Nov 27
- Macdona, TX 78054 · last Feb 20, first Dec 3
Frequently asked questions
- When is the last frost in San Antonio, TX?
- For ZIP code 78254, the average last spring frost (32°F) is February 18, based on NOAA 1991-2020 climate normals for the San Antonio/Seaworld, TX weather station. There is a 1-in-10 chance of a frost after March 16.
- When is the first frost in San Antonio, TX?
- The average first fall frost (32°F) is December 9. There is a 1-in-10 chance of frost by November 17, so tender plants are at risk from that point on.
- How long is the growing season in 78254?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 296 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.