Home/Maricopa County, AZ
Arizona -- population 4,418,836

Maricopa County, AZ 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

Maricopa County, AZ hazard summary: FEMA National Risk Index rated Very High; EPA radon zone 2 of 3; most frequently recorded hazard is thunderstorm wind (672 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

Maricopa County has 1,850,862 housing units. About 14% 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
32,353
2010-2019
216,171
2000-2009
406,348
1990-1999
338,881
1980-1989
313,500
1970-1979
289,005
1960-1969
123,542
1950-1959
92,649
1940-1949
21,705
1939 or earlier
16,708

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

Heat WaveVery High
Inland FloodingVery High
WildfireRelatively High
HailVery High
Strong WindVery High
Source: FEMA National Risk Index

Recorded Storm History (2015-2024)

NOAA recorded 1,280 storm events in Maricopa County between 2015 and 2024. This is actual event history, not a risk model -- the counts below are individually logged storms, not a prediction.

Thunderstorm Wind
672
Flash Flood
387
Hail
82
Flood
51
Heavy Rain
46
Lightning
17
Funnel Cloud
14
Tornado
11
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 Maricopa 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.