Frostline.info

Frost line depth in Kern County, California

Frost reaches about 4 inches in typical soil across Kern County, from 0″ in the mildest ZIP code to 9″ in the coldest. Codes in this climate commonly set footing depth at 12 inches (code minimum).

Shallow frost
Estimated frost depth
4″
typical silt/loam soil
Typical code footing depth
12″ minimum
rule of thumb for this climate
Design freezing index
18
°F-days, 100-year winter
ZIP codes covered
43
#23 of 58 counties in CA (1 = deepest)
4″ 0″12″24″36″ ground frozen
Est. frost (typical soil) Typical code footing depth Clay–sand range

Frost depth by soil type

Soil typeEst. frost depth
Sand / gravel (drains well)5″
Silt / loam (typical yard soil)4″
Clay (holds water)4″

County average. Methodology.

Verify before you dig. These are climate-based estimates. The legally required frost depth is the figure your building department publishes in its IRC Table R301.2 (climatic and geographic design criteria). Call the Kern County building or permitting office in California and call 811 before digging.

Frost depth by ZIP code in Kern County

ZIPCityEst. frostCode range
93203Arvin2″12″ minimum
93205Bodfish5″12–18″
93206Buttonwillow2″12″ minimum
93215Delano1″12″ minimum
93224Fellows2″12″ minimum
93225Frazier Park2″12″ minimum
93226Glennville7″12–18″
93238Kernville4″12″ minimum
93240Lake Isabella5″12–18″
93241Lamont1″12″ minimum
93243Lebec5″12–18″
93249Lost Hills2″12″ minimum
93250Mc Farland1″12″ minimum
93251Mc Kittrick2″12″ minimum
93252Maricopa2″12″ minimum
93255Onyx6″12–18″
93263Shafter1″12″ minimum
93268Taft2″12″ minimum
93280Wasco1″12″ minimum
93283Weldon5″12–18″
93285Wofford Heights4″12″ minimum
93287Woody6″12–18″
93301Bakersfield0″12″ minimum
93304Bakersfield0″12″ minimum
93305Bakersfield0″12″ minimum
93306Bakersfield1″12″ minimum
93307Bakersfield0″12″ minimum
93308Bakersfield0″12″ minimum
93309Bakersfield0″12″ minimum
93311Bakersfield0″12″ minimum
93312Bakersfield0″12″ minimum
93313Bakersfield0″12″ minimum
93314Bakersfield1″12″ minimum
93501Mojave8″12–18″
93505California City7″12–18″
93516Boron6″12–18″
93518Caliente7″12–18″
93523Edwards7″12–18″
93527Inyokern5″12–18″
93531Keene7″12–18″
93555Ridgecrest5″12–18″
93560Rosamond7″12–18″
93561Tehachapi9″12–18″

What this means for your project in Kern County

Deck footings & piers

Footings must bear below the frost line and at least 12″ below undisturbed ground. For planning in this area, budget for holes around 12″ deep until your permit office confirms the exact figure.

Fence posts

Set posts at least one-third of their above-ground height. Where frost heave is a problem, carry concrete footings below the frost line (about 12″ here in typical soil) and bell or taper the bottom.

Water & irrigation lines

Bury supply lines below the frost depth. Your water utility or plumbing code sets the minimum cover; freezing is rare, but exposed pipes still need insulation.

Slabs & frost-protected foundations

Frost-protected shallow foundations (IRC R403.3) use the 100-year air freezing index — 18 °F-days here — to size perimeter insulation, letting footings sit shallower than the frost line.

Weather stations used

NOAA weather stationDistance100-yr AFI
Kern River Ph No 1, CA7 mi0
Bakersfield, CA15 mi0
Tejon Rancho, CA24 mi6
Glennville, CA24 mi58

Nearby counties

Common questions

What is the frost line depth in Kern County?

About 4 inches in typical soil, based on NOAA's 100-year air freezing index. Across the county's ZIP codes the estimate runs from 0 to 9 inches.

How deep should footings be in Kern County, California?

Codes in climates like this commonly require 12 inches (code minimum). The Kern County building department publishes the required frost depth in its adopted code (IRC Table R301.2).

Does frost depth vary within Kern County?

Yes. Estimates differ by 9 inches between the coldest and mildest ZIP codes, mostly from latitude and elevation. Check your own ZIP below.