Frost Line Depth in St. Louis County, Minnesota
- Minnesota state rule
- Checked Oct 2026
- Sources
State-set value
60in
152 cm · 5 ft
60 in (Minnesota rule)
Set by the state: Minnesota Rules 1303.1600, Zone I (St. Louis County).
Source and how we checked
St. Louis County does not publish its own value; the state rule applies.
Document: revisor.mn.gov
Climate: 189 nights a year at or below 32 °F (NOAA 1991–2020, Eveleth Wwtp, 8.4 mi).
Checked Oct 2026. Report a correction
How deep is the frost line in St. Louis County?
Minnesota sets the frost footing depth for St. Louis County at 60 in (152 cm). Footings, piers and other permanent supports must reach at least this depth (IRC R403.1.4.1).
Who sets the frost line depth in St. Louis County?
Minnesota writes this depth into its statewide residential code, so St. Louis County’s building department enforces the state’s number rather than setting its own. See how Minnesota sets frost line depth.
How deep do footings, decks and water lines need to be in St. Louis County?
House or garage footing in St. Louis County: dig at least 60 in (152 cm). Below the frost line and at least 12 in deep (IRC R403.1.4).
| Project | Depth | Rule |
|---|---|---|
| House or garage footing | 60 in | Below the frost line and at least 12 in deep (IRC R403.1.4) |
| Deck footing (attached) | 60 in | Below the frost line and at least 12 in deep (IRC R507.3) |
| Water service line | 66 in | 6 in below the frost line and at least 12 in deep (IRC P2603.5) |
| Fence post bottom | 60 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. Louis County?
- J
- F
- M
- A
- M
- J
- J
- A
- S
- O
- N
- D
Average lows are at or below freezing from Nov to Apr. 189 nights a year reach 32 °F or colder; Jan is coldest, with an average low of -1.5 °F.
NOAA 1991–2020 climate normals, Eveleth Wwtp station, 8.4 mi away, elevation 1,445 ft.
Monthly temperatures as a table
| °F | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Low | -1.5 | 1.7 | 14.3 | 27.6 | 40.7 | 51.1 | 55.6 | 53.8 | 45.3 | 33.4 | 19.9 | 6.4 |
| High | 16.5 | 22.1 | 35.3 | 49 | 63.1 | 72.3 | 77.2 | 75.5 | 66 | 50.9 | 34.5 | 21.8 |
St. Louis County has more freezing nights than 8 of the 9 other Minnesota places we track. The Minnesota median is 159. Coldest: Itasca County; mildest: Winona County.
How likely is the soil in St. Louis County to heave?
USDA rates the sampled soil around St. Louis County as 60% moderate, 40% high for frost action (main soils: Eaglesnest, Greenwood, Eveleth).
USDA NRCS soil survey, 9 sample points within 2 mi. Higher frost action means more risk of heave; see frost heave.
How do you confirm the frost line before you dig in St. Louis County?
St. Louis County at a glance
- Frost line depth
- 60 in (Minnesota rule)
- Population (2023 est.)
- 200,514
- Mean annual temperature
- 38.9 °F
- ZIP codes (52)
- 55602 · 55616 · 55702 · 55703 · 55705 · 55706 · 55708 · 55710 · 55711 · 55713 · 55717 · 55719 · 55720 · 55723 · 55724 · 55725 · 55731 · 55732 · 55733 · 55734 · 55736 · 55738 · 55741 · 55746 · 55750 · 55751 · 55758 · 55763 · 55765 · 55768 · 55771 · 55772 · 55779 · 55781 · 55782 · 55790 · 55792 · 55796 · 55798 · 55802 · 55803 · 55804 · 55805 · 55806 · 55807 · 55808 · 55810 · 55811 · 55812 · 55814 · 56649 · 56669