Frost Line Depth in Whittier, California
- Whittier’s adopted code
- Checked Oct 2026
- Sources
Verified
12in
30 cm · 1 ft
12–24 in
Set in the building code Whittier has adopted.
Source and how we checked
Document: library.municode.com
Climate: 0 nights a year at or below 32 °F (NOAA 1991–2020, Fullerton Municipal Airport, 7 mi).
Checked Oct 2026. Report a correction
How deep is the frost line in Whittier?
Whittier's building authority lists a frost line depth of 12–24 in (30–61 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 Whittier?
California leaves the frost line depth to each city or county, and Whittier fills it in when it adopts the residential code. The value above comes from Whittier’s own document on library.municode.com. See how California sets frost line depth.
How deep do footings, decks and water lines need to be in Whittier?
House or garage footing in Whittier: dig at least 12 in (30 cm). Below the frost line and at least 12 in deep (IRC R403.1.4).
| Project | Depth | Rule |
|---|---|---|
| House or garage footing | 12 in | Below the frost line and at least 12 in deep (IRC R403.1.4) |
| Deck footing (attached) | 12 in | Below the frost line and at least 12 in deep (IRC R507.3) |
| Water service line | 18 in | 6 in below the frost line and at least 12 in deep (IRC P2603.5) |
| Fence post bottom | 12 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 Whittier?
- J
- F
- M
- A
- M
- J
- J
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- N
- D
Whittier never averages a low below freezing. 0 nights a year reach 32 °F or colder; Dec is coldest, with an average low of 45.6 °F.
NOAA 1991–2020 climate normals, Fullerton Municipal Airport station, 7 mi away, elevation 96 ft.
Monthly temperatures as a table
| °F | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Low | 46.4 | 48.3 | 51.5 | 53.8 | 58.1 | 62.6 | 66.1 | 66.4 | 64.6 | 58.3 | 50.7 | 45.6 |
| High | 68.8 | 69 | 71 | 74.2 | 75.7 | 79 | 84.4 | 86.7 | 85.4 | 80.3 | 74 | 68.1 |
Whittier has fewer freezing nights than 166 of the 208 other California places we track. The California median is 3. Coldest: El Dorado County; mildest: San Diego.
What frost line depth do towns near Whittier use?
4 official codes near Whittier are verified; each links to its document.
How likely is the soil in Whittier to heave?
USDA rates the sampled soil around Whittier as 100% none for frost action (main soils: Thums, Soper, Apollo).
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 Whittier?
Whittier at a glance
- Frost line depth
- 12–24 in
- County
- Los Angeles County
- Population (2023 est.)
- 84,143
- Mean annual temperature
- 66.2 °F
- ZIP codes (8)
- 90601 · 90602 · 90603 · 90604 · 90605 · 90606 · 90670 · 91733