Frost Line Depth in Okanogan County, Washington
- Okanogan County’s adopted code
- Checked Oct 2026
- Sources
Verified
24in
61 cm · 2 ft
Set in the building code Okanogan County has adopted.
Source and how we checked
Document: okanogancounty.gov
Climate: 145 nights a year at or below 32 °F (NOAA 1991–2020, Omak Airport, 12 mi).
Checked Oct 2026. Report a correction
How deep is the frost line in Okanogan County?
Okanogan County's building authority sets the frost line depth at 24 in (61 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 Okanogan County?
Washington leaves the frost line depth to each city or county, and Okanogan County fills it in when it adopts the residential code. The value above comes from Okanogan County’s own document on okanogancounty.gov. See how Washington sets frost line depth.
How deep do footings, decks and water lines need to be in Okanogan County?
House or garage footing in Okanogan County: dig at least 24 in (61 cm). Below the frost line and at least 12 in deep (IRC R403.1.4).
| Project | Depth | Rule |
|---|---|---|
| House or garage footing | 24 in | Below the frost line and at least 12 in deep (IRC R403.1.4) |
| Deck footing (attached) | 24 in | Below the frost line and at least 12 in deep (IRC R507.3) |
| Water service line | 30 in | 6 in below the frost line and at least 12 in deep (IRC P2603.5) |
| Fence post bottom | 24 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 Okanogan County?
- J
- F
- M
- A
- M
- J
- J
- A
- S
- O
- N
- D
Average lows are at or below freezing from Nov to Mar. 145 nights a year reach 32 °F or colder; Jan is coldest, with an average low of 23.3 °F.
NOAA 1991–2020 climate normals, Omak Airport station, 12 mi away, elevation 1,296 ft.
Monthly temperatures as a table
| °F | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Low | 23.3 | 25.2 | 31.1 | 36.8 | 45.1 | 51.1 | 58.1 | 56.8 | 48.4 | 37.5 | 28.9 | 23.3 |
| High | 32.8 | 39.8 | 52.5 | 62.8 | 72.4 | 79.1 | 89.4 | 88.8 | 78.2 | 60.7 | 43 | 32.5 |
Okanogan County has more freezing nights than 45 of the 47 other Washington places we track. The Washington median is 54. Coldest: Chelan County; mildest: Lakewood.
How likely is the soil in Okanogan County to heave?
USDA rates the sampled soil around Okanogan County as 100% moderate for frost action (main soils: Wynhoff, Conconully, Donavan).
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 Okanogan County?
Okanogan County at a glance
- Frost line depth
- 24 in
- Population (2023 est.)
- 43,712
- Mean annual temperature
- 49.9 °F
- ZIP codes (22)
- 98812 · 98813 · 98814 · 98816 · 98819 · 98827 · 98829 · 98833 · 98834 · 98840 · 98841 · 98844 · 98846 · 98849 · 98855 · 98856 · 98859 · 98862 · 99116 · 99124 · 99155 · 99166