Home/Riverside County, CA
California -- population 2,416,838

Riverside County, CA Property Research

Real data from four public sources, not an internal estimate: the EPA's radon zone classification, Census housing-age records, FEMA's natural hazard risk index, and NOAA's recorded storm history for this county. Every figure below links to where it actually comes from.

Hazard Summary

Riverside County, CA hazard summary: FEMA National Risk Index rated Very High; EPA radon zone 2 of 3; most frequently recorded hazard is flash flood (133 events, 2015-2024).

Radon Risk

Zone 2 -- moderate potential. EPA predicts an average indoor radon screening level between 2 and 4 pCi/L for this county.

This is a county-wide prediction from geology and soil data, not a measurement of any specific home -- EPA recommends testing every home regardless of zone. See our guide on negotiating radon mitigation after inspection.

Source: EPA Map of Radon Zones

Housing Age

Riverside County has 860,042 housing units. About 17% were built in 1969 or earlier -- old enough that knob-and-tube wiring, lead-based paint, and galvanized supply lines are all realistic possibilities worth checking for, not just a general inspection line item.

2020 or later
10,516
2010-2019
77,279
2000-2009
211,828
1990-1999
125,449
1980-1989
174,866
1970-1979
117,287
1960-1969
61,443
1950-1959
49,469
1940-1949
14,208
1939 or earlier
17,697

Does knob-and-tube wiring have to be replaced before closing?

Source: U.S. Census Bureau, ACS 5-Year Estimates, Table B25034

Natural Hazard Risk

FEMA rates Riverside County's overall natural hazard risk as Very High, relative to the rest of the country.

WildfireVery High
Inland FloodingVery High
EarthquakeVery High
LandslideRelatively High
Heat WaveRelatively High
Source: FEMA National Risk Index

Recorded Storm History (2015-2024)

NOAA recorded 373 storm events in Riverside County between 2015 and 2024. This is actual event history, not a risk model -- the counts below are individually logged storms, not a prediction.

Flash Flood
133
Flood
73
Heavy Rain
57
Thunderstorm Wind
56
Debris Flow
25
Lightning
16
Hail
7
Funnel Cloud
6
Source: NOAA National Centers for Environmental Information, Storm Events Database

Guides Relevant to This County's Housing Stock

How to Spot Polybutylene Pipes Before Buying a HouseCan You Get Home Insurance with Polybutylene Plumbing?Does a Standard Home Inspection Check for Asbestos?What Is a Federal Pacific Stab-Lok Panel and Why Inspectors Flag It?Do Federal Pacific (FPE) Panels Affect Insurance Like Zinsco Panels?Will a Zinsco Panel Fail a 4-Point Inspection?

Get Your Free Property Report

BeforeRegret pulls live seismic hazard data, validates the address, and builds era- and county-specific inspection priorities and seller questions into one report -- with anything not yet independently verified clearly labeled, not guessed at.

Get Your First Report Free

This page reports what these four public agencies have published for Riverside County as a whole -- it is not an assessment of any specific address or property, and does not replace a licensed home inspection, radon test, or insurance review for a specific home. Data last checked August 10, 2026.