Frostline.info

Frost line depth in Riverside County, California

Frost reaches about 2 inches in typical soil across Riverside County, from 0″ in the mildest ZIP code to 7″ in the coldest. Codes in this climate commonly set footing depth at 12 inches (code minimum).

Source: NOAA 100-year air freezing index (1951–80 station records) · Last reviewed

Shallow frost
Estimated frost depth
2″
typical silt/loam soil
Typical code footing depth
12″ minimum
rule of thumb for this climate
Design freezing index
3
°F-days, 100-year winter
ZIP codes covered
68
#39 of 58 counties in CA (1 = deepest)
2″ 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)2″
Silt / loam (typical yard soil)2″
Clay (holds water)1″

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 Riverside County building or permitting office in California and call 811 before digging.

Frost depth by ZIP code in Riverside County

ZIPCityEst. frostCode range
91752Mira Loma0″12″ minimum
92201Indio0″12″ minimum
92203Indio0″12″ minimum
92210Indian Wells0″12″ minimum
92211Palm Desert0″12″ minimum
92220Banning1″12″ minimum
92223Beaumont1″12″ minimum
92225Blythe0″12″ minimum
92230Cabazon1″12″ minimum
92234Cathedral City0″12″ minimum
92236Coachella0″12″ minimum
92240Desert Hot Springs0″12″ minimum
92241Desert Hot Springs0″12″ minimum
92253La Quinta0″12″ minimum
92254Mecca0″12″ minimum
92260Palm Desert0″12″ minimum
92262Palm Springs0″12″ minimum
92264Palm Springs0″12″ minimum
92270Rancho Mirage0″12″ minimum
92274Thermal0″12″ minimum
92276Thousand Palms0″12″ minimum
92282Whitewater0″12″ minimum
92320Calimesa1″12″ minimum
92501Riverside0″12″ minimum
92503Riverside0″12″ minimum
92504Riverside0″12″ minimum
92505Riverside0″12″ minimum
92506Riverside0″12″ minimum
92507Riverside0″12″ minimum
92508Riverside0″12″ minimum
92509Jurupa Valley0″12″ minimum
92518March Air Reserve Base0″12″ minimum
92530Lake Elsinore0″12″ minimum
92532Lake Elsinore0″12″ minimum
92536Aguanga7″12–18″
92539Anza6″12–18″
92543Hemet1″12″ minimum
92544Hemet1″12″ minimum
92545Hemet1″12″ minimum
92548Homeland0″12″ minimum
92551Moreno Valley0″12″ minimum
92553Moreno Valley0″12″ minimum
92555Moreno Valley0″12″ minimum
92557Moreno Valley0″12″ minimum
92561Mountain Center3″12″ minimum
92562Murrieta0″12″ minimum
92563Murrieta3″12″ minimum
92567Nuevo1″12″ minimum
92570Perris0″12″ minimum
92571Perris0″12″ minimum
92582San Jacinto1″12″ minimum
92583San Jacinto1″12″ minimum
92584Menifee0″12″ minimum
92585Menifee0″12″ minimum
92586Menifee0″12″ minimum
92587Menifee0″12″ minimum
92590Temecula4″12″ minimum
92591Temecula5″12–18″
92592Temecula5″12–18″
92595Wildomar0″12″ minimum
92596Winchester4″12″ minimum
92860Norco0″12″ minimum
92878Corona0″12″ minimum
92879Corona0″12″ minimum
92880Corona0″12″ minimum
92881Corona0″12″ minimum
92882Corona0″12″ minimum
92883Corona0″12″ minimum

What this means for your project in Riverside 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 — 3 °F-days here — to size perimeter insulation, letting footings sit shallower than the frost line.

Weather stations used

NOAA weather stationDistance100-yr AFI
Beaumont 1 E, CA10 mi1
Redlands, CA22 mi0
Elsinore, CA23 mi0
Palm Springs, CA25 mi0

Nearby counties

Common questions

What is the frost line depth in Riverside County?

About 2 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 7 inches.

How deep should footings be in Riverside County, California?

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

Does frost depth vary within Riverside County?

Yes. Estimates differ by 7 inches between the coldest and mildest ZIP codes, mostly from latitude and elevation. Check your own ZIP below.