Frost Line Depth in San Juan County, NM: New Mexico Codes Range 6

No official local value

No official frost line depth is published for San Juan County.

No verified code nearby; verified New Mexico codes range 6–16 in.

Source and how we checked

We searched this place’s own code and website and found no published frost line depth.

Climate: 140 nights a year at or below 32 °F (NOAA 1991–2020, Farmington Ag Sci Cnt, 12.3 mi).

Checked Oct 2026. Report a correction

Footings Deck Water line Fence post

6–16 inrange of verified New Mexico codes
140nights a year at or below 32 °F
83%of nearby soil rated “low” for frost action (USDA)

Does San Juan County have an official frost line depth?

No adopted frost line depth found for San Juan County in its official documents (checked Oct 2026). No verified code lies near San Juan County; the New Mexico codes we verified range from 6 to 16 in. Ask the building department for San Juan County’s own number before you dig.

What frost line depth does San Juan County use for footings under Table R301.2(1)?

Call 811 at least a few working days before you dig, so buried lines are marked.
Confirm the frost line depth with the San Juan County building department.
Ask whether your project needs a permit (decks, larger sheds and footings usually do).
Dig below 16 in (the deepest verified state value) unless the building department tells you otherwise.
Book the footing inspection before you pour concrete.

How deep do footings, decks and water lines need to be in San Juan County?

Drawn with the deepest New Mexico official value (16 in). Confirm San Juan County’s own depth before you dig.

House or garage footing Deck footing Water service line Fence post

House or garage footing in San Juan County: dig at least 16 in (41 cm). Below the frost line and at least 12 in deep (IRC R403.1.4).

Using the nearby official value of 16 in until San Juan County confirms its own
Project	Depth	Rule
House or garage footing	16 in	Below the frost line and at least 12 in deep (IRC R403.1.4)
Deck footing (attached)	16 in	Below the frost line and at least 12 in deep (IRC R507.3)
Water service line	22 in	6 in below the frost line and at least 12 in deep (IRC P2603.5)
Fence post bottom	16 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 Juan County?

Average lows are at or below freezing from Nov to Mar. 140 nights a year reach 32 °F or colder; Jan is coldest, with an average low of 20 °F.

NOAA 1991–2020 climate normals, Farmington Ag Sci Cnt station, 12.3 mi away, elevation 5,625 ft.

Monthly temperatures as a table

°F	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Low	20	24.5	30.6	36.5	45.4	54.6	61.3	59.8	52	40.1	28.8	20.8
High	41.1	48	57.7	65.4	75	86.4	90.2	87.2	80	67.5	53.3	41.7

San Juan County has more freezing nights than 10 of the 16 other New Mexico places we track. The New Mexico median is 124. Coldest: McKinley County; mildest: Lea County.

How likely is the soil in San Juan County to heave?

Low 83%Moderate 17%

USDA rates the sampled soil around San Juan County as 83% low, 17% moderate for frost action (main soils: Doak, Avalon, Shiprock).

USDA NRCS soil survey, 9 sample points within 2 mi. Higher frost action means more risk of heave; see frost heave.

San Juan County at a glance

Frost line depth: No official local value
Population (2023 est.): 120,675
Mean annual temperature: 52.8 °F
ZIP codes (22): 81137 · 86514 · 87037 · 87313 · 87325 · 87328 · 87364 · 87401 · 87402 · 87410 · 87412 · 87413 · 87415 · 87416 · 87417 · 87418 · 87419 · 87420 · 87421 · 87455 · 87461 · 87499