Frost Line Depth in San Marcos, Texas
- 4 verified codes nearby
- Checked Oct 2026
No official local value
No official frost line depth is published for San Marcos.
Nearby official codes require 6–12 in (4 verified codes).
Source and how we checked
We searched this place’s own code and website and found no published frost line depth.
Climate: 20 nights a year at or below 32 °F (NOAA 1991–2020, San Marcos, 1.1 mi).
Checked Oct 2026. Report a correction
Does San Marcos have an official frost line depth?
No adopted frost line depth found for San Marcos in its official documents (checked Oct 2026). The nearest official values, from codes we verified, are 6 to 12 in. Use the deepest of them until the building department confirms San Marcos’s own number.
What frost line depth does San Marcos use for footings under Table R301.2(1)? Is it 6 in, like Kyle?
How deep do footings, decks and water lines need to be in San Marcos?
Drawn with the deepest nearby official value (12 in). Confirm San Marcos’s own depth before you dig.
House or garage footing in San Marcos: 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 | 18 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 Marcos?
- J
- F
- M
- A
- M
- J
- J
- A
- S
- O
- N
- D
San Marcos never averages a low below freezing. 20 nights a year reach 32 °F or colder; Jan is coldest, with an average low of 38.9 °F.
NOAA 1991–2020 climate normals, San Marcos station, 1.1 mi away, elevation 665 ft.
Monthly temperatures as a table
| °F | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Low | 38.9 | 42.4 | 49.5 | 56.3 | 64.9 | 71.7 | 73.4 | 73.7 | 68.5 | 58.1 | 48.3 | 40.8 |
| High | 62.3 | 66.6 | 73.1 | 79.8 | 86.2 | 92.4 | 95.7 | 96.8 | 90.5 | 82.1 | 71.5 | 63.7 |
San Marcos has fewer freezing nights than 113 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 Marcos use?
4 official codes near San Marcos are verified; each links to its document.
| Place | Verified frost line | Distance |
|---|---|---|
| Kyle | 6 in | 9 mi away |
| Austin | 12 in | 31 mi away |
| Cedar Park | 6 in | 45 mi away |
| Leander | 6 in | 49 mi away |
How likely is the soil in San Marcos to heave?
USDA rates the sampled soil around San Marcos as 100% none for frost action (main soils: Branyon, Lewisville, Oakalla).
USDA NRCS soil survey, 9 sample points within 2 mi. Higher frost action means more risk of heave; see frost heave.
San Marcos at a glance
- Frost line depth
- No official local value
- County
- Hays County
- Population (2023 est.)
- 71,569
- Mean annual temperature
- 68.6 °F
- ZIP codes (4)
- 78640 · 78655 · 78656 · 78666