Frost Line Depth in Walla Walla County, Washington
- 2 verified codes nearby
- Checked Oct 2026
No official local value
No official frost line depth is published for Walla Walla County.
Nearby official codes require 24 in (2 verified codes).
Source and how we checked
We searched this place’s own code and website and found no published frost line depth.
Climate: 70 nights a year at or below 32 °F (NOAA 1991–2020, Walla Walla Regional Airport, 14.4 mi).
Checked Oct 2026. Report a correction
Does Walla Walla County have an official frost line depth?
No adopted frost line depth found for Walla Walla County in its official documents (checked Oct 2026). The nearest official values, from codes we verified, are 24 in. Use the deepest of them until the building department confirms Walla Walla County’s own number.
What frost line depth does Walla Walla County use for footings under Table R301.2(1)? Is it 24 in, like Franklin County?
How deep do footings, decks and water lines need to be in Walla Walla County?
Drawn with the deepest nearby official value (24 in). Confirm Walla Walla County’s own depth before you dig.
House or garage footing in Walla Walla 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 Walla Walla County?
- J
- F
- M
- A
- M
- J
- J
- A
- S
- O
- N
- D
Average lows are at or below freezing from Dec to Jan. 70 nights a year reach 32 °F or colder; Dec is coldest, with an average low of 30.2 °F.
NOAA 1991–2020 climate normals, Walla Walla Regional Airport station, 14.4 mi away, elevation 1,166 ft.
Monthly temperatures as a table
| °F | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Low | 30.7 | 32.9 | 37.8 | 42.5 | 49.3 | 55.1 | 62.4 | 61.7 | 53.9 | 43.9 | 35.6 | 30.2 |
| High | 41.9 | 46.5 | 55.8 | 62.5 | 71.4 | 79 | 90.1 | 88.6 | 78.5 | 63.4 | 49.2 | 41 |
Walla Walla County has more freezing nights than 28 of the 47 other Washington places we track. The Washington median is 54. Coldest: Chelan County; mildest: Lakewood.
What frost line depth do towns near Walla Walla County use?
2 official codes near Walla Walla County are verified; each links to its document.
| Place | Verified frost line | Distance |
|---|---|---|
| Franklin County | 24 in | 28 mi away |
| Pasco | 24 in | 31 mi away |
How likely is the soil in Walla Walla County to heave?
USDA rates the sampled soil around Walla Walla County as 100% high for frost action (main soils: Ritzville, Esquatzel).
USDA NRCS soil survey, 9 sample points within 2 mi. Higher frost action means more risk of heave; see frost heave.
Walla Walla County at a glance
- Frost line depth
- No official local value
- Population (2023 est.)
- 61,568
- Mean annual temperature
- 54.3 °F
- ZIP codes (8)
- 99323 · 99324 · 99329 · 99348 · 99360 · 99361 · 99362 · 99363