Pima County, Arizona Natural Disaster Risk
FEMA National Risk Index assessment · AZ
HighComposite Risk Score
National percentile: 99th
Pima County faces high composite natural disaster risk (NRI Risk Index score 99.1, 99th national percentile), driven primarily by heat wave and wildfire exposure. Expected annual loss across all 18 hazard types is $531M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
Overall natural disaster risk in Pima County is high, with a National Risk Index score of 99.1 out of 100 — placing it in the 99th national percentile and in the upper tier of natural-disaster risk nationally. The score blends Expected Annual Loss, Social Vulnerability, and Community Resilience across all 18 FEMA hazard types.
Risk here concentrates in heat wave (prolonged periods of extreme heat that threaten health and infrastructure) at Very High risk — $133M in expected annual loss and about 8.09 events per year; wildfire (uncontrolled fires that spread across wildland and into communities) at High risk — $38M in expected annual loss and about 0.00 events per year; and riverine flood (rivers and streams overflowing their banks after heavy rain or snowmelt) at Very High risk — $347M in expected annual loss and about 12.82 events per year. Across all hazards, FEMA estimates $531M in expected annual loss for a population of 1.04M.
Beyond physical exposure, Pima County has a medium social vulnerability rating (how susceptible the population is to harm) and a low community resilience rating (its capacity to prepare for and recover from disasters). Both measures sit toward the lower end, indicating relatively modest population sensitivity.
The county's disaster history tells the same story: Pima County has received 15 federal disaster declarations since 1966, including 8 for flood events and 3 for fire events. The most recent was Big Horn Fire (fire), declared in June 2020.
Among 15 Arizona counties, Pima County ranks #2 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Heat Wave | Very High | 8.09 / yr | $133M |
| Wildfire | High | 0.00 / yr | $38M |
| Riverine Flood | Very High | 12.82 / yr | $347M |
| Lightning | Very High | 42.77 / yr | $3M |
| Hail | Medium | 0.24 / yr | $2M |
| Earthquake | Medium | 0.01 / yr | $6M |
| Strong Wind | Medium | 0.79 / yr | $1M |
| Winter Weather | Medium | 1.80 / yr | $200K |
| Drought | Medium | 57.26 / yr | $459K |
| Landslide | Very Low | 2.14 / yr | $2K |
| Avalanche | Very Low | 0.01 / yr | $358 |
| Tornado | Low | 0.26 / yr | $688K |
| Hurricane | Very Low | 0.02 / yr | $5K |
| Cold Wave | Very Low | 0.00 / yr | $150 |
| Coastal Flood | Very Low | 0.00 / yr | $0 |
| Ice Storm | Very Low | 0.00 / yr | $0 |
| Tsunami | Very Low | 0.00 / yr | $0 |
| Volcanic Activity | Very Low | 0.00 / yr | $0 |
Disaster History
Pima County has received 15 federal disaster declarations since 1966, most recently Big Horn Fire in June 2020. Most frequent causes: Flood (8), Fire (3), Biological (2).
| Declared | Type | Disaster |
|---|---|---|
| June 2020 | Fire | Big Horn Fire |
| April 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| September 2006 | Severe Storm | Severe Storms and Flooding |
| September 2005 | Hurricane | Hurricane Katrina Evacuation |
| July 2003 | Fire | Aspen Fire |
| June 2003 | Fire | Aspen Fire |
| January 1993 | Flood | Severe Storms, Tornadoes & Flooding |
| December 1990 | Flood | Severe Storms & Flooding |
| October 1983 | Flood | Severe Storms & Flooding |
Showing the 10 most recent of 15 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Pima County?
Pima County has a composite FEMA National Risk Index score of 99.1 out of 100, placing it in the High category and the 99th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Pima County?
The three highest-rated hazards are Heat Wave (Very High, $133M EAL), Wildfire (High, $38M EAL), Riverine Flood (Very High, $347M EAL). These account for most of the county's expected annual losses.
How does Pima County compare to other Arizona counties?
Pima County ranks #2 of 15 Arizona counties for overall natural disaster risk, with a high rating.
How many federally declared disasters has Pima County had?
FEMA records 15 federal disaster declarations for Pima County since 1966, most often 8 for flood events and 3 for fire events. The most recent was Big Horn Fire, declared in June 2020.
What does Expected Annual Loss (EAL) mean?
EAL is FEMA's estimate of average annual dollar losses from natural hazards, calculated from historical event data and exposure models. Pima County's $531M EAL is a statistical average, not a guarantee for any specific year or address.