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Phoenix survival atlas

Maricopa County, Arizona

Reviewed · Data: FEMA National Risk Index v1.20 (December 2025) · U.S. Census Bureau Vintage 2025 · By SOS.city, made by the people for the people
In an emergency, call 911

Phoenix’s biggest natural hazards are inland flooding, heat waves and wildfire. In FEMA’s National Risk Index they make up 96% of the natural-hazard risk for Maricopa County, home to all of Phoenix’s 1.7 million residents. FEMA rates the county’s overall risk Very High. Here is what to do for each, step by step.

People
1,665,481
Census estimate, July 1, 2025. No. 5 in the U.S.
County
Maricopa County
All of Phoenix’s residents. FEMA rates counties, not cities.
Overall risk
Very High
Score 99.87 of 100. No. 4 of the 10 largest U.S. cities.
Expected loss
$2.2 billion
A year, from all 18 natural hazards (FEMA estimate).
Top 3 hazards
96%
of the county’s risk comes from these three: Inland flooding · Heat wave · Wildfire.

What to do for Phoenix’s top hazards

The one rule to remember, then the first steps, word for word from our guides. Each guide lists its sources.

No. 1 · 51% of the risk · Very High

Inland flooding

FEMA score 99.87: higher than 99.8% of U.S. counties. Expected loss $1.1 billion a year.

RememberTurn around, don't drown.
  1. Get to high ground now.
  2. Never walk, swim or drive into floodwater. 6 inches of moving water can knock you down; 12 inches carries away most cars.
  3. Car stalls in rising water: get out to higher ground if you safely can. Trapped in fast water: stay inside; if water rises inside, get on the roof.
Every step: What to do in a flood or flash flood
Source // National Weather Service: Turn Around Don’t Drown · Ready.gov: Floods
No. 2 · 44% of the risk · Very High

Heat wave

FEMA score 100.00: the highest of any U.S. county. Expected loss $958 million a year.

RememberGet somewhere cool. Check on anyone who lives alone.
  1. Use air conditioning, or go to a library, mall or cooling center.
  2. Heat stroke signs: confusion, slurred speech, collapse; hot, dry or soaked skin; 103°F or higher.
  3. Call 911.
Every step: What to do in extreme heat and heat stroke
Source // National Weather Service: Heat safety · CDC/NIOSH: Heat-related illnesses
No. 3 · 1.9% of the risk · Relatively High

Wildfire

FEMA score 99.61: higher than 99.6% of U.S. counties. Expected loss $42.2 million a year.

RememberLeave early. Know two ways out.
  1. Grab the go-bags, the people and the pets. Go.
  2. Use the routes officials name, not shortcuts.
  3. In smoke, wear an N95. Cloth masks don't filter it.
Every step: What to do when a wildfire is coming
Source // Ready.gov: Wildfires · Ready, Set, Go! (International Association of Fire Chiefs)
Emergency911
Poison Help1-800-222-1222
Can’t reach family?Text, don’t call. Texts often get through when calls don’t.

All 18 natural hazards in Phoenix, ranked

Ranked by each hazard’s share of Maricopa County’s risk in FEMA’s National Risk Index. The score compares the county with every other U.S. county for that one hazard.

#HazardShare of riskFEMA ratingScoreExpected loss a yearThe rule
1 Inland flooding 51% Very High 99.87 $1.1 billion Turn around, don't drown.
2 Heat wave 44% Very High 100.00 $958 million Get somewhere cool. Check on anyone who lives alone.
3 Wildfire 1.9% Relatively High 99.61 $42.2 million Leave early. Know two ways out.
4 Earthquake 1.4% Relatively Moderate 96.81 $30.7 million Drop. Cover. Hold on.
5 Hail 1.1% Very High 99.52 $24.2 million Get indoors, away from windows.
6 Strong wind 0.4% Very High 99.07 $8.8 million Shelter in an interior room, away from windows.
7 Tornado 0.2% Relatively Moderate 84.00 $5.4 million Lowest floor, interior room, cover your head.
8 Drought 0.2% Relatively High 97.70 $4.6 million Store water now: 1 gallon per person per day.
9 Lightning <0.1% Relatively High 95.45 $2.1 million When thunder roars, go indoors.
10 Winter weather <0.1% Relatively Low 38.73 $47,000 Stay in your shelter, or stay with your car.
11 Landslide <0.1% Relatively Low 83.90 $28,000 Follow local alerts. Leave when officials say so.
12 Hurricane <0.1% Very Low 26.57 $12,000 Know your evacuation zone. Told to go? Go early.
13 Avalanche <0.1% Very Low 32.89 $144 Check your local avalanche center before backcountry travel.
– Coastal flooding – Not applicable – – Run from the water. Hide from the wind.
– Cold wave – No rating – – One warm room. Never heat with an oven or a grill.
– Ice storm – Not applicable – – Stay off the roads. One warm room.
– Tsunami – Not applicable – – Strong or long shaking near the sea: go high now.
– Volcanic activity – Not applicable – – Evacuate early. In ashfall, stay in and wear an N95.

Source // FEMA National Risk Index v1.20 (December 2025), county 04013. Rules: SOS.city survival guides.

How to read these numbers

  • Share of risk. For each hazard, FEMA estimates the loss each year to buildings, people and farms, then adjusts it for social vulnerability and community resilience. The county’s overall risk is the sum of all 18, so the share shows how much of it each hazard carries.
  • Score. A percentile from 0 to 100. A score of 99.5 means the county’s risk for that hazard is higher than 99.5% of U.S. counties.
  • Rating. FEMA sorts counties into five groups, from Very Low to Very High.
  • Big places rank high. Expected losses grow with the number of people and buildings exposed, so large urban counties rank high on many hazards. A high rating means plan for it, not that it will happen this year.
  • County, not street. These ratings cover the whole county. For flood risk at your address, look it up on the FEMA Flood Map Service Center.
  • Maricopa County is rated Relatively Low for social vulnerability and Very Low for community resilience. Both feed into its overall rating.

Questions people ask

What natural disasters is Phoenix most at risk for?

Phoenix’s biggest natural hazards are inland flooding, heat waves and wildfire. In FEMA’s National Risk Index they make up 96% of the natural-hazard risk for Maricopa County, home to all of Phoenix’s 1.7 million residents. FEMA rates the county’s overall risk Very High.

How does FEMA rate Phoenix’s overall disaster risk?

FEMA’s National Risk Index rates the overall risk of Maricopa County Very High, with a score of 99.87 out of 100. The score is a percentile: Maricopa County’s overall risk is higher than 99.8% of U.S. counties. Expected losses from natural hazards there average $2.2 billion a year.

What should I do first to get ready in Phoenix?

Write down your top three: inland flooding, heat waves and wildfire. Turn on Emergency Alerts on every phone and sign up for your county’s alerts. Store water: 1 gallon per person per day for at least 3 days, 2 weeks if you can.

Sources

Every number on this page comes from these public datasets. We check them when we review the page.

General safety information, not medical advice. In an emergency, call 911 and follow local officials.

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