Frost Dates for San Antonio, TX 78230

San Antonio has 59 ZIP codes. The San Antonio, TX frost page lists all of them with their dates.

Last spring frost March 4 · First fall frost November 21 · 262 frost-free days · USDA Zone 9a

Frost probability for 78230

Frost10%50%90%
Spring (last frost)March 29March 4February 8
Fall (first frost)October 31November 21December 12

Dates come from NOAA 1971–2000 freeze probabilities at the nearest reporting station (40.0 km away); the 50% date is the median year.

Month by month in San Antonio

MonthWhat to do
JanuaryStart peppers and eggplant indoors 8–10 weeks before your last frost (around March 4). Start tomatoes about two weeks later, 6–8 weeks before last frost.
FebruaryStart herbs, basil, and squash indoors (4–6 weeks before frost). Direct sow peas, spinach, and lettuce if soil is workable.
MarchLast frost around March 4. Transplant cold-hardy crops (broccoli, kale, cabbage). Harden off tomato and pepper seedlings.
AprilFrost has passed. Transplant tomatoes, peppers, and basil outdoors. Direct sow beans, cucumbers, squash, and zucchini.
MaySuccession plant lettuce and greens. Keep beds weeded and watered consistently.
JuneHarvest regularly to encourage production. Monitor for pests and disease.
JulyMidsummer: harvest beans, zucchini, cucumbers. Start brassica seeds indoors for fall.
AugustDirect sow carrots and beets for fall harvest. Start fall broccoli and kale indoors.
SeptemberDirect sow carrots and beets for fall harvest. Start fall broccoli and kale indoors.
OctoberFirst fall frost approaching (around November 21). Transplant fall brassicas. Sow spinach, arugula, and radishes.
NovemberFirst frost around November 21. Harvest tomatoes and peppers before frost. Cover cold-hardy crops with row covers to extend the season.
DecemberHarvest remaining cold-hardy crops: kale, carrots, and beets. Plant garlic bulbs for next year.

What grows in a 262-day season

Frequently Asked Questions

What is the last frost date for San Antonio, TX (ZIP 78230)?

The median last spring frost date for San Antonio, TX (ZIP code 78230) is around March 4. This is the 50th-percentile date — meaning half of all years see frost end before this date. Use the 10% and 90% dates to understand the full range of risk in your area.

What is the first fall frost date in San Antonio, TX?

The median first fall frost date for San Antonio, TX is around November 21. Plan to harvest or protect frost-sensitive crops like tomatoes and peppers at least a week before this date to avoid losses.

How long is the growing season in San Antonio, TX?

The frost-free growing season in San Antonio is about 262 days. This window — from your last spring frost to your first fall frost — is when warm-season vegetables thrive. Cold-hardy crops like kale, spinach, and peas can extend your season by weeks on either side.

What USDA hardiness zone is San Antonio, TX?

Based on frost date patterns, San Antonio falls approximately in 9a. USDA hardiness zones are determined by average annual minimum winter temperatures and guide both plant selection and planting timing for your location.

When should I start tomatoes indoors in San Antonio, TX?

Start tomato seeds indoors 6–8 weeks before your last frost date (around March 4). For San Antonio, that's roughly January 8 to January 22. Transplant outdoors 1–2 weeks after your last frost.

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