Frost Line Depth in San Antonio, Texas
- San Antonio’s adopted code
- Checked Oct 2026
- Sources
Verified
0in
No frost depth required
Set in the building code San Antonio has adopted.
Footings still go at least 12 in (30 cm) below undisturbed ground (IRC R403.1.4).
Source and how we checked
Document: up.codes
Climate: 22 nights a year at or below 32 °F (NOAA 1991–2020, San Antonio Incarnate Word, 3.2 mi).
Checked Oct 2026. Report a correction
How deep is the frost line in San Antonio?
San Antonio's building authority sets the frost line depth at 0 in (0 cm). Footings, piers and other permanent supports still go at least 12 in below undisturbed ground (IRC R403.1.4).
Who sets the frost line depth in San Antonio?
Texas leaves the frost line depth to each city or county, and San Antonio fills it in when it adopts the residential code. The value above comes from San Antonio’s own document on up.codes. See how Texas sets frost line depth.
How deep do footings, decks and water lines need to be in San Antonio?
House or garage footing in San Antonio: dig at least 12 in (30 cm). Below the frost line and at least 12 in deep (IRC R403.1.4).
| Project | Depth | Rule |
|---|---|---|
| House or garage footing | 12 in | Below the frost line and at least 12 in deep (IRC R403.1.4) |
| Deck footing (attached) | 12 in | Below the frost line and at least 12 in deep (IRC R507.3) |
| Water service line | 12 in | 6 in below the frost line and at least 12 in deep (IRC P2603.5) |
| Fence post bottom | 12 in | No code rule; common practice is below the frost line |
Work out posts, concrete and footing sizes with the fence post depth calculator or the deck footing calculator.
How cold does it get in San Antonio?
- J
- F
- M
- A
- M
- J
- J
- A
- S
- O
- N
- D
San Antonio never averages a low below freezing. 22 nights a year reach 32 °F or colder; Jan is coldest, with an average low of 40.2 °F.
NOAA 1991–2020 climate normals, San Antonio Incarnate Word station, 3.2 mi away, elevation 700 ft.
Monthly temperatures as a table
| °F | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Low | 40.2 | 43.8 | 51 | 57.4 | 65.7 | 72 | 74.1 | 74.1 | 68.8 | 59.2 | 49 | 41.4 |
| High | 63.2 | 67.5 | 73.8 | 80.1 | 85.7 | 91.7 | 94 | 95.3 | 89.5 | 81.7 | 71.4 | 64.2 |
San Antonio has fewer freezing nights than 111 of the 168 other Texas places we track. The Texas median is 32. Coldest: Amarillo; mildest: Brownsville.
What frost line depth do towns near San Antonio use?
2 official codes near San Antonio are verified; each links to its document.
How likely is the soil in San Antonio to heave?
USDA rates the sampled soil around San Antonio as 100% none for frost action (main soils: Houston Black, Austin, Branyon).
USDA NRCS soil survey, 9 sample points within 2 mi. Higher frost action means more risk of heave; see frost heave.
How do you confirm the frost line before you dig in San Antonio?
San Antonio at a glance
- Frost line depth
- 0 in
- County
- Bexar County
- Population (2023 est.)
- 1,495,295
- Mean annual temperature
- 69 °F
- ZIP codes (68)
- 78015 · 78023 · 78056 · 78073 · 78109 · 78112 · 78154 · 78201 · 78202 · 78203 · 78204 · 78205 · 78207 · 78208 · 78209 · 78210 · 78211 · 78212 · 78213 · 78214 · 78215 · 78216 · 78217 · 78218 · 78219 · 78220 · 78221 · 78222 · 78223 · 78224 · 78225 · 78226 · 78227 · 78228 · 78229 · 78230 · 78231 · 78232 · 78233 · 78234 · 78235 · 78236 · 78237 · 78238 · 78239 · 78240 · 78242 · 78243 · 78244 · 78245 · 78247 · 78248 · 78249 · 78250 · 78251 · 78252 · 78253 · 78254 · 78255 · 78256 · 78257 · 78258 · 78259 · 78260 · 78261 · 78263 · 78264 · 78266