Frost Line Depth in Rochester, MN: 42 in (Minnesota rule)

State-set value

42in

107 cm · 3 ft 6 in

42 in (Minnesota rule)

Set by the state: Minnesota Rules 1303.1600, Zone II (Olmsted County).

Source and how we checked

Rochester does not publish its own value; the state rule applies.

Document: revisor.mn.gov

Climate: 156 nights a year at or below 32 °F (NOAA 1991–2020, Rochester International Airport, 7.6 mi).

Checked Oct 2026. Report a correction

Footings Deck Water line Fence post

156nights a year at or below 32 °F
56%of nearby soil rated “high” for frost action (USDA)

How deep is the frost line in Rochester?

Minnesota sets the frost footing depth for Rochester at 42 in (107 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 Rochester?

Minnesota writes this depth into its statewide residential code, so Rochester’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 Rochester?

House or garage footing Deck footing Water service line Fence post

House or garage footing in Rochester: dig at least 42 in (107 cm). Below the frost line and at least 12 in deep (IRC R403.1.4).

Minimum depths in Rochester with a 42 in frost line
Project	Depth	Rule
House or garage footing	42 in	Below the frost line and at least 12 in deep (IRC R403.1.4)
Deck footing (attached)	42 in	Below the frost line and at least 12 in deep (IRC R507.3)
Water service line	48 in	6 in below the frost line and at least 12 in deep (IRC P2603.5)
Fence post bottom	42 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 Rochester?

Average lows are at or below freezing from Nov to Mar. 156 nights a year reach 32 °F or colder; Jan is coldest, with an average low of 7 °F.

NOAA 1991–2020 climate normals, Rochester International Airport station, 7.6 mi away, elevation 1,304 ft.

Monthly temperatures as a table

°F	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Low	7	10.7	23.4	35.1	47.1	57.5	60.8	58.3	50.4	38	25.6	13.6
High	22.5	26.7	39.9	55.3	68	77.6	80.3	78	71.8	57.9	41.7	28

Rochester has fewer freezing nights than 5 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 Rochester to heave?

Moderate 33%High 56%

USDA rates the sampled soil around Rochester as 11% low, 33% moderate, 56% high for frost action (main soils: Downs, Brodale, Whalan).

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 Rochester?

Call 811 (Gopher State One Call) at least a few working days before you dig, so buried lines are marked.
Confirm the frost line depth with the Rochester building department.
Ask whether your project needs a permit (decks, larger sheds and footings usually do).
Dig below 42 in unless the building department tells you otherwise.
Book the footing inspection before you pour concrete.

Rochester at a glance

Frost line depth: 42 in (Minnesota rule)
County: Olmsted County
Population (2023 est.): 122,413
Mean annual temperature: 44.8 °F
ZIP codes (8): 55901 · 55902 · 55903 · 55904 · 55905 · 55906 · 55960 · 55976