Frost Line Depth in St. George, UT: Utah Codes Range 30

No official local value

No official frost line depth is published for St. George.

No verified code nearby; verified Utah codes range 30–36 in.

Source and how we checked

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

Climate: 62 nights a year at or below 32 °F (NOAA 1991–2020, St George, 3.3 mi).

Checked Oct 2026. Report a correction

Footings Deck Water line Fence post

30–36 inrange of verified Utah codes
62nights a year at or below 32 °F
44%of nearby soil rated “none” for frost action (USDA)

Does St. George have an official frost line depth?

No adopted frost line depth found for St. George in its official documents (checked Oct 2026). No verified code lies near St. George; the Utah codes we verified range from 30 to 36 in. Ask the building department for St. George’s own number before you dig.

What frost line depth does St. George 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 St. George building department.
Ask whether your project needs a permit (decks, larger sheds and footings usually do).
Dig below 36 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 St. George?

Drawn with the deepest Utah official value (36 in). Confirm St. George’s own depth before you dig.

House or garage footing Deck footing Water service line Fence post

House or garage footing in St. George: dig at least 36 in (91 cm). Below the frost line and at least 12 in deep (IRC R403.1.4).

Using the nearby official value of 36 in until St. George confirms its own
Project	Depth	Rule
House or garage footing	36 in	Below the frost line and at least 12 in deep (IRC R403.1.4)
Deck footing (attached)	36 in	Below the frost line and at least 12 in deep (IRC R507.3)
Water service line	42 in	6 in below the frost line and at least 12 in deep (IRC P2603.5)
Fence post bottom	36 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 St. George?

Average lows are at or below freezing from Dec to Jan. 62 nights a year reach 32 °F or colder; Dec is coldest, with an average low of 27.9 °F.

NOAA 1991–2020 climate normals, St George station, 3.3 mi away, elevation 2,857 ft.

Monthly temperatures as a table

°F	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Low	28.4	32.4	39	45.7	55.5	64.5	71.7	70.3	60.7	47.3	34.7	27.9
High	54	59.3	67.8	75	85.4	96.4	101.9	99.9	92.4	78.8	63.8	53

St. George has fewer freezing nights than 25 of the 25 other Utah places we track. The Utah median is 118. Coldest: Summit County; mildest: St. George.

How likely is the soil in St. George to heave?

None 44%Low 21%Moderate 36%

USDA rates the sampled soil around St. George as 44% none, 21% low, 36% moderate for frost action (main soils: Fluvaquents, Junction, Winkel).

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

St. George at a glance

Frost line depth: No official local value
County: Washington County
Population (2023 est.): 104,578
Mean annual temperature: 62.7 °F
ZIP codes (4): 84765 · 84770 · 84780 · 84790