Frost Line Depth in Hawthorne, CA: Frost Rarely Reaches the Ground

No official local value

Frost rarely reaches the ground in Hawthorne.

Nearby official codes require 12 in (4 verified codes).

Footings still go at least 12 in (30 cm) below undisturbed ground (IRC R403.1.4).

Source and how we checked

We searched this place’s own code and website and found no published frost line depth.

Climate: 0 nights a year at or below 32 °F (NOAA 1991–2020, Hawthorne Municipal Airport, 1 mi).

Checked Oct 2026. Report a correction

Footings Deck Water line Fence post

12 in4 verified codes within 29 mi
0nights a year at or below 32 °F
100%of nearby soil rated “none” for frost action (USDA)

Does Hawthorne have an official frost line depth?

No adopted frost line depth found for Hawthorne in its official documents (checked Oct 2026). The nearest official values, from codes we verified, are 12 in. Use the deepest of them until the building department confirms Hawthorne’s own number.

What frost line depth does Hawthorne use for footings under Table R301.2(1)? Is it 12 in, like Paramount?

Call 811 at least a few working days before you dig, so buried lines are marked.
Confirm the frost line depth with the Hawthorne building department.
Ask whether your project needs a permit (decks, larger sheds and footings usually do).
Dig below 12 in (the deepest nearby value) unless the building department tells you otherwise.
Book the footing inspection before you pour concrete.

How deep do footings, decks and water lines need to be in Hawthorne?

Drawn with the deepest nearby official value (12 in). Confirm Hawthorne’s own depth before you dig.

House or garage footing Deck footing Water service line Fence post

House or garage footing in Hawthorne: dig at least 12 in (30 cm). Below the frost line and at least 12 in deep (IRC R403.1.4).

Minimum depths in Hawthorne with a 12 in frost line
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 Hawthorne?

Hawthorne never averages a low below freezing. 0 nights a year reach 32 °F or colder; Dec is coldest, with an average low of 48.8 °F.

NOAA 1991–2020 climate normals, Hawthorne Municipal Airport station, 1 mi away, elevation 63 ft.

Monthly temperatures as a table

°F	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Low	49.2	50.6	52.7	54.8	58.4	61.5	64.7	65.3	64.5	60.3	53.6	48.8
High	67.3	66.8	67.8	69.7	70.7	73.1	77.2	78.7	78.5	76	71.7	66.4

Hawthorne 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 Hawthorne use?

4 official codes near Hawthorne are verified; each links to its document.

Official frost line depths near Hawthorne
Place	Verified frost line	Distance
Paramount	12 in	10 mi away
Norwalk	12 in	15 mi away
Whittier	12 in	19 mi away
Santa Ana	12 in	29 mi away

How likely is the soil in Hawthorne to heave?

None 100%

USDA rates the sampled soil around Hawthorne as 100% none for frost action (main soils: Windfetch, Typic Xerorthents, Centinela).

USDA NRCS soil survey, 9 sample points within 2 mi. Higher frost action means more risk of heave; see frost heave.

Hawthorne at a glance

Frost line depth: No official local value
County: Los Angeles County
Population (2023 est.): 83,364
Mean annual temperature: 64.5 °F
ZIP codes (6): 90045 · 90250 · 90260 · 90278 · 90303 · 90304