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Frost data
Frost line depth in Pennsylvania
The short answer
Pennsylvania publishes no single statewide frost depth. Pennsylvania runs a statewide Uniform Construction Code but leaves the frost-line column for each municipality to complete. 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 Pennsylvania works out to a minimum of 12 inches. Source: PA Department of Labor & Industry, Uniform Construction Code (UCC) Home.
Pennsylvania’s UCC adopts the model residential code across the commonwealth, and like most such adoptions it treats the climate table as something local jurisdictions fill in. So the state has a uniform code and a non-uniform frost depth, and the figure that binds your project belongs to your municipality rather than to Harrisburg.
The range is real. Philadelphia sits at the mild end of the state and Erie at the cold end, and the commonwealth’s own weather record puts roughly seven weeks between the earliest and latest median first freeze. Rather than average that into a number nobody publishes, we list the jurisdiction figures we could verify and point you at your code office.
Pennsylvania has not amended the water service depth rule, so the model-code language applies: not less than 12 inches deep and not less than 6 inches below the local frost line.
By jurisdiction
What Pennsylvania jurisdictions publish
With no statewide figure, these are the depths real building departments have published.
| Jurisdiction | Frost depth | Source |
|---|---|---|
| City of Erie, PA | 48 in | City of Erie, Bureau of Building Standards and Safety, design criter… |
| City of Allentown, PA | 36 in | City of Allentown, residential building plan review checklist, Table… |
| City of Lancaster, PA | 36 in | City of Lancaster, residential construction guidelines: exterior wal… |
These are the jurisdictions whose published figure we could read and verify, so it isn’t a complete list of Pennsylvania building departments. Yours may differ, and yours is the one that governs your permit.
The weather behind the number
When it freezes in Pennsylvania
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 |
|---|---|---|---|---|---|
| ALLENTOWN INTL AP | October 24 | November 4 | November 29 | April 20 | 40 |
| JOHNSTOWN CAMBRIA CO AP | October 21 | November 2 | November 21 | April 29 | 54 |
| LANCASTER AP | October 25 | November 5 | December 1 | April 18 | 34 |
| PHILADELPHIA NE AP | November 7 | November 19 | December 18 | April 4 | 20 |
| PORT MEADVILLE AP | October 23 | November 4 | November 26 | April 30 | 49 |
| YORK AP | October 18 | October 30 | November 22 | April 27 | 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 160 Pennsylvania stations with published normals, the median first 32°F night falls around October 19 and the median station records 47 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 CLARENCE, where the median first freeze is September 27, to PHILA FRANKLIN INST at November 17.
The median Pennsylvania station reaches freezing around 19 October and records about 47 nights a year below 20°F, close to Ohio. The spread runs from Clarence, on the Allegheny plateau, at 27 September, to the Franklin Institute station in central Philadelphia at 17 November. Fifty days between the two ends of one state is a good argument against a single commonwealth-wide frost figure, and probably part of why there is not one.
Water lines
Burial depth for a water service line in Pennsylvania
Pennsylvania's UCC leaves the Table R301.2(1) frost-line-depth column for each local jurisdiction to fill in, so the IRC P2603.5.1 baseline governs statewide: water service piping buried below the locally-set frost line and not less than 12 inches below grade (Philadelphia's own adopted table sets frost line depth at 30 inches).
Under the model rule that Pennsylvania 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
Pennsylvania frost line questions
How deep is the frost line in Pennsylvania?
Pennsylvania publishes no statewide figure. The Uniform Construction Code adopts the model residential code and leaves the frost-line column of the climate table for each municipality to complete, so the depth in Erie is not the depth in Philadelphia. Your municipal code office has the number that governs your permit.
Does the Pennsylvania UCC apply everywhere in the state?
The code applies statewide, but municipalities choose whether to enforce it themselves or have the Department of Labor and Industry administer it through a third-party agency. Either way there is a code office responsible for your address, and that office holds the frost figure along with the rest of the local amendments.
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 Pennsylvania frost figure was researched against the body that publishes it, and it’s recorded with a confidence note of “local only, verified” 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.
- PA Department of Labor & Industry, Uniform Construction Code (UCC) Home The Pennsylvania 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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