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Frost data
Frost line depth in Utah
The short answer
Utah publishes no single statewide frost depth. Utah leaves the figure to local jurisdictions, and the published range is wide: about 12 inches in St. George and 30 along the Wasatch Front and in the eastern counties. Footings have to bear below that depth, and a water service line has to sit at least six inches below it and at least twelve inches down, which in Utah works out to a minimum of 12 inches. Source: Utah Division of Administrative Rules â Bulletin filing for Rule R156-56 (Statewide Amendments to the IRC).
Utah’s statewide rule, R156-56, adopts the model residential code without filling in the frost line, so the number comes from the jurisdiction. The published figures track elevation rather than latitude, which is what you would expect in a state that runs from 2,200 feet at St. George to over 6,000 in the Uinta Basin. St. George uses 12 inches. Duchesne County and the Greater Salt Lake Municipal Services District both publish 30.
Two and a half feet of difference inside one state is the practical reason a Utah frost figure cannot be generalised. It is also why a contractor moving between southern Utah and the Wasatch Front is quoting a materially different excavation for the same footing detail.
Utah has not amended the water service burial rule, so the model-code language governs and the frost figure sets the floor: 30 inches along the Wasatch Front, and the twelve-inch floor in St. George, where the frost figure is shallow enough that the floor is the binding number.
By jurisdiction
What Utah jurisdictions publish
With no statewide figure, these are the depths real building departments have published.
| Jurisdiction | Frost depth | Source |
|---|---|---|
| St. George, UT (Washington County) | 12 in | City of St. George Building Department, Design Criteria â |
| Duchesne County, UT | 30 in | Duchesne County General Design Information for Construction â |
| Greater Salt Lake Municipal Services District, UT | 30 in | Greater Salt Lake MSD, Codes and Design Criteria â |
These are the jurisdictions whose published figure we could read and verify, so it isn’t a complete list of Utah building departments. Yours may differ, and yours is the one that governs your permit.
The weather behind the number
When it freezes in Utah
NOAA 1991 to 2020 normals at representative stations across the state.
| Station | First 32°F | First 28°F | First 20°F | Last 32°F | Nights below 20°F |
|---|---|---|---|---|---|
| BRIGHAM CITY 28 WNW | October 5 | October 15 | November 3 | May 12 | 75 |
| CEDAR CITY MUNI AP | September 29 | October 9 | November 1 | May 21 | 64 |
| LOGAN CACHE AP | October 2 | October 13 | November 5 | May 8 | 73 |
| PRICE CARBON CO AP | October 12 | October 22 | November 12 | May 3 | 67 |
| VERNAL MUNICIPAL AP | October 7 | October 19 | November 8 | May 6 | 90 |
| WENDOVER AP AWOS | October 23 | November 1 | November 19 | April 18 | 45 |
Dates are the median: half of years cross that threshold earlier, half later. “no normal” means NOAA publishes none for that station, which at a warm station means it does not reliably get that cold. Source: NOAA NCEI U.S. Climate Normals, 1991-2020, retrieved 2026-09-09.
Across all 169 Utah stations with published normals, the median first 32°F night falls around October 5 and the median station records 68 nights a year below 20°F, which is the coldest threshold NOAA counts and a decent proxy for a hard freeze rather than a light frost. The state’s spread runs from RANDOLPH, where the median first freeze is September 1, to HITE RS at November 20.
Utah’s median station logs about 68 nights a year below 20°F, more than Michigan, which surprises people who file the state under desert. That is elevation doing the work. The spread inside the state is close to three months: Randolph in the Bear River valley reaches its median first freeze on 1 September, while Hite on the Colorado River holds out until 20 November. Any statewide Utah figure, frost or freeze, is an average of two very different places.
Water lines
Burial depth for a water service line in Utah
Utah's statewide rule amending the IRC (Utah Admin. Code R156-56) does not amend the water-service burial provision, so the IRC baseline applies statewide, with the actual frost line set locally (roughly 12 inches in St. George to 30+ inches along the Wasatch Front / higher-elevation counties).
Under the model rule that Utah works from, a water service line goes Water service pipe shall be installed not less than 12 inches (305 mm) deep and not less than 6 inches (152 mm) below the frost line.
which puts the floor here at 12 inches. 2021 International Residential Code, Section P2603.5 (Freezing), ICC free code viewer. Your water utility may specify more for the portion of the service it owns, and the building department that issues the permit has the final say. The national picture is on how deep water lines are buried.
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Common questions
Utah frost line questions
How deep is the frost line in Utah?
It depends heavily on elevation and there is no statewide number. St. George publishes 12 inches; Duchesne County and the Greater Salt Lake Municipal Services District both publish 30. Check with the jurisdiction issuing your permit, because in Utah the gap between two figures inside the state is larger than the gap between many whole states.
Does high elevation in Utah mean deeper frost than northern states?
It can mean more freezing nights, which is why Utah’s median station records more nights below 20°F than Michigan’s does. Design frost depth follows the air-freezing index, which combines how Design frost depth reflects how long a winter stays cold as well as how cold it gets, and Utah’s dry, sunny winters mean the ground does not always freeze as deep as the night-time air temperatures alone would suggest. That is one reason the published Utah figures are shallower than the freeze counts imply.
Next
Where to go from here
The frost depth is the digging number. It won’t tell you whether your pipes are at risk this winter, and the two pages that will are at what temperature pipes freeze and when pipes freeze where you live, both with a ZIP lookup. If a pipe has already split, burst pipe repair cost covers the repair and the water damage behind it, and what to do about a frozen pipe is the page to open first.
Other state pages: Minnesota, Iowa, Michigan, Ohio, Indiana, Illinois, Virginia, Wisconsin, and all fifty in the national table.
Where these numbers come from
The Utah frost figure was researched against the body that publishes it, and it’s recorded with a confidence note of “” in our source ledger. Freeze dates are NOAA normals for stations in the state, picked by a fixed rule rather than by hand: first-order stations, spread west to east. The full method is on our methodology page.
- Freeze dates and cold-night counts: NOAA NCEI U.S. Climate Normals, 1991 to 2020, annual and seasonal by station. Retrieved 2026-09-09. Field definitions are in the by-variable readme.
- ZIP code locations: U.S. Census Bureau 2023 ZIP Code Tabulation Area gazetteer, matched to the nearest station by great-circle distance.
- Utah Division of Administrative Rules â Bulletin filing for Rule R156-56 (Statewide Amendments to the IRC) The Utah frost depth figure and basis.
- City of St. George, UT Building Department â Design Criteria The Utah frost depth figure and basis.
- Duchesne County, UT â General Design Information for Construction The Utah frost depth figure and basis.
- Greater Salt Lake Municipal Services District â Codes and Design Criteria The Utah frost depth figure and basis.
- 2021 International Residential Code, Section P2603.5 (Freezing), ICC free code viewer The water service line burial rule.
The full method, including how we pick a station and what we do when there is not one close enough, is on our methodology page.
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