Frost dates for ZIP 78023 (San Antonio, TX)
Average last spring and first fall frost dates with 10%, 50% and 90% odds, from NOAA's 1991–2020 climate normals for the nearest weather station, Boerne, TX (12 miles away).
- Average last spring frostMar 1550% chance of a 32°F freeze after this date
- Average first fall frostNov 1350% chance of a 32°F freeze by this date
- Growing season (frost-free)243 daysmedian, 32°F threshold
- USDA hardiness zone8b15 to 20°F avg. coldest night
Last spring frost odds
| Chance of a 32°F freeze after this date | Date |
|---|---|
| 90% (early: most years still freeze after this) | Feb 23 |
| 50% (the "average" last frost) | Mar 15 |
| 10% (safe-side: only 1 year in 10 freezes later) | Apr 8 |
Most gardeners plant frost-tender crops (tomatoes, peppers, basil) after the 50% date, and closer to the 10% date for less risk.
First fall frost odds
| Chance the first 32°F freeze has happened by this date | Date |
|---|---|
| 10% (early: 1 year in 10 freezes this soon) | Oct 31 |
| 50% (the "average" first frost) | Nov 13 |
| 90% (late: most years have frozen by now) | Dec 4 |
Light frost, freeze and hard freeze
| Threshold | Last spring (50%) | First fall (50%) |
|---|---|---|
| 36°F (light frost possible on clear, calm nights) | Apr 1 | Nov 4 |
| 32°F (freeze) | Mar 15 | Nov 13 |
| 28°F (hard freeze) | Mar 2 | Nov 27 |
n/a means NOAA did not publish a date at that threshold for this station (usually because it rarely gets that cold).
This week in San Antonio
Soil temperature now
2-inch depth
70°F 55°F or warmer
24-hour average · latest 72°F, as of Oct 17, 7:00 PM CDT
Estimate Not a measurement at this ZIP: distance-weighted average of EAA Field Research Park (23 mi), Headwaters Ranch (32 mi), Holt Oaks Ranch (33 mi).
4-inch depth
72°F 55°F or warmer
24-hour average · latest 74°F, as of Oct 17, 7:00 PM CDT
Estimate Not a measurement at this ZIP: distance-weighted average of EAA Field Research Park (23 mi), Headwaters Ranch (32 mi), Holt Oaks Ranch (33 mi).
Fall: Texas A&M AgriLife times fall pre-emergent (for winter weeds such as annual bluegrass) to soil cooling to about 70°F for several days. The 50–55°F band is the spring trigger. Always read and follow the product label.
7-day forecast and frost risk
No frost in the 7-day forecast.
| Period | High | Low | Forecast |
|---|---|---|---|
| Tonight | 48° | Partly Cloudy | |
| Sunday | 72° | 52° | Mostly Sunny |
| Monday | 76° | 57° | Mostly Sunny |
| Tuesday | 81° | 59° | Mostly Sunny |
| Wednesday | 84° | 60° | Mostly Sunny |
| Thursday | 86° | 61° | Sunny |
| Friday | 86° | 63° | Mostly Sunny |
National Weather Service forecast, issued Oct 17, 8:28 PM CDT. Frost can form above 32°F on clear, calm nights. Full NWS forecast.
Free frost alerts for 78023
An email when the National Weather Service forecasts a freeze for this ZIP, plus the spring soil-temperature heads-up. At most a few a month.
Alerts open soon. This form is a preview and doesn't send anything yet.
Where these numbers come from
Station: Boerne, TX (NOAA GHCN-Daily ID USC00410902), elevation 1,445 ft, 12.3 miles from the ZIP's center point. NOAA completeness flag: S (standard, 24+ years).
Nearby stations
| Station | Distance | Last frost (50%) | First frost (50%) |
|---|---|---|---|
| San Antonio/seaworld, TX | 12 mi | Feb 18 | Dec 9 |
| San Antonio Intl AP, TX | 17 mi | Feb 26 | Nov 28 |
| San Antonio Kelly AFB, TX | 19 mi | Feb 22 | Dec 2 |
The average last-frost dates of these stations span 28 days, a rough guide to local variation. See data sources & methods.
Questions
When is the last frost in 78023?
The average (50% chance) last spring freeze of 32°F for ZIP 78023 is March 15. For a safer planting date, use April 8, when only 1 year in 10 still sees a later freeze.
When is the first frost in 78023?
The average first fall freeze is November 13. In 1 year in 10 it comes by October 31.
What hardiness zone is 78023?
ZIP 78023 is in USDA zone 8b (15 to 20°F average coldest winter night), per the 2023 USDA Plant Hardiness Zone Map ZIP listing.
Other ZIP codes in Bexar County
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