Maricopa County, AZ flood risk and hazards
FEMA rates riverine flooding and heat wave risk as Very High in Maricopa County, AZ. Modeled losses from natural hazards (expected annual loss) average about $2.2 billion a year, for a population of 4,418,836. These county figures come from the FEMA National Risk Index, December 2025 release. Observation windows vary by metric and sit beside the tables below.
- Modeled expected annual loss
- $2.20 billion / year
- US loss rank
- #5 of 3,232
- State loss rank
- #1 of 15
- Loss per resident
- $497 · state $504 · US $459
- FEMA overall risk rating
- Very High
Arizona county modeled loss
- Positive estimates to $21.0 million
- Above $21.0 million to $42.5 million
- Above $42.5 million to $91.5 million
- Above $91.5 million to $130.9 million
- Above $130.9 million to $2.20 billion
- No FEMA estimate
Maricopa County, AZ ranks #1 of 15 in the state for modeled expected annual loss; the outline locates it.
View chart data
Is Maricopa County at risk of flooding?
FEMA labels riverine flooding Very High and coastal flooding Not Applicable. Modeled annual riverine flood loss is $1,119,501,534; coastal flood loss is Not Applicable. These are separate hazards and county totals. A rating describes relative county risk. It does not locate water at a building or establish a flood zone. Read missing statuses using the source documentation. Keep both source labels when comparing counties. Read the county rating versus flood-zone guide before requesting a location check.
Look up an address and its flood zone through FEMA’s Flood Map Service Center.
The local hazard planning document is Maricopa County Multi-Jurisdictional Hazard Mitigation Plan. Local governments use this plan to set out hazards and proposed projects.
What natural hazards affect Maricopa County most?
Show tabular data
| County | Modeled expected annual loss (USD/year) | Overall risk rating |
|---|---|---|
| Maricopa County, AZ | 2,195,561,910.06 | Very High |
Show tabular data
| Hazard | Source label | Observation window |
|---|---|---|
| Coastal flooding | Not Applicable | 1996-2023 |
| Riverine flooding | Very High | 1996-2023 |
| Hurricane | Very Low | 1851-2024 |
| Wildfire | Relatively High | 1996-2023 |
| Earthquake | Relatively Moderate | 1996-2023 |
| Tornado | Relatively Moderate | 1950-2023 |
| Heat wave | Very High | 2005-2024 |
How have heat and rain changed in Maricopa County?
Hot days
Hot days increased between the two decades.
View chart data
| Place | Days / year |
|---|---|
| 1991–2000 | 127.80 |
| 2016–2025 | 140.70 |
Warm nights
Warm nights increased between the two decades.
View chart data
| Place | Days / year |
|---|---|
| 1991–2000 | 71.10 |
| 2016–2025 | 89.90 |
Heavy-precipitation days
Heavy-precipitation days round to 0.0 in both decades; hollow marks confirm the zero state.
View chart data
| Place | Days / year |
|---|---|
| 1991–2000 | 0.00 |
| 2016–2025 | 0.00 |
Humid-heat days
Humid-heat days increased between the two decades.
View chart data
| Place | Days / year |
|---|---|
| 1991–2000 | 45.00 |
| 2016–2025 | 54.60 |
| Measure | 1991–2000 | 2016–2025 | Change |
|---|---|---|---|
| Hot days · ≥35°C (95°F) | 127.8 | 140.7 | +12.9 |
| Humid-heat days · heat index ≥103°F (39.4°C) | 45.0 | 54.6 | +9.6 |
| Warm nights · ≥24°C (75.2°F) | 71.1 | 89.9 | +18.8 |
| Heavy-rain days · ≥50 mm (≈2 in) | 0.0 | 0.0 | 0.0 |
| Annual maximum daily precipitation · mm | 25.2 | 26.9 | +1.8 |
Counts are days per year; a grid-cell zero does not mean the county had no such events. Thresholds, time bases and limits: county climate method.
Methodology & sensor cross-check notes
Hot-day cross-check: NOAA’s county-average daily maximum temperature gives 123.6 → 130.2 hot days a year (+6.6); NASA gives 127.8 → 140.7 (+12.9). Both series show an increase, with different counts and change sizes. The footprints differ, so agreement does not validate either count. Warm nights and precipitation were not cross-checked. Humid-heat row: Copernicus (ECMWF) reanalysis. It uses a different regional grid from the NASA measures.
No statistical significance, cause or future trend is established; this does not change the FEMA ratings above.
Climate data: NASA · Population context: US Census Bureau · Hot-day cross-check: NOAA county climate records · Humid heat: Copernicus (ECMWF). Method, sources and limitations · Climate JSON · Data credits.
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direction"}}How does El Niño affect Maricopa County winters?
Strong El Niño winter precipitation
7 of 9 strong El Niño winters were wetter than normal. The vertical line marks 100% of normal precipitation.
View chart data
| Winter | Precipitation (% of normal) |
|---|---|
| 1957–58 | 51.492 |
| 1965–66 | 211.692 |
| 1972–73 | 113.943 |
| 1982–83 | 152.079 |
| 1991–92 | 183.766 |
| 1997–98 | 199.627 |
| 2009–10 | 176.025 |
| 2015–16 | 64.183 |
| 2023–24 | 131.574 |
NOAA and IRI both give 100% odds that El Niño conditions (tropical Pacific ONI of at least 0.5°C, not a local weather forecast) are present this winter. In Maricopa County, 7 of 9 past strong El Niño winters were wetter than normal; the median winter had 152% of normal precipitation (rain and melted snow). The driest, 1957–58, had 51%.
| Winter | ONI | Precipitation | Temp. | Heavy days | Claims |
|---|---|---|---|---|---|
| 1957–58 | 1.7 | 51% | +1.8°F | 0 | — |
| 1965–66 | 1.6 | 212% | −2.5°F | 1 | — |
| 1972–73 | 1.8 | 114% | −2.2°F | 0 | — |
| 1982–83 | 2.1 | 152% | −0.4°F | 0 | 3 (#13) |
| 1991–92 | 1.5 | 184% | +1.0°F | 0 | 4 (#10) |
| 1997–98 | 2.4 | 200% | −1.8°F | 0 | 5 (#8) |
| 2009–10 | 1.5 | 176% | −0.7°F | 1 | 12 (#5) |
| 2015–16 | 2.6 | 64% | +0.3°F | 0 | 3 (#13) |
| 2023–24 | 2.0 | 132% | −0.4°F | 0 | 3 (#13) |
Winter normals and temperature baseline
Maricopa County normals, 1990–91 to 2019–20 winters: 3.2 inches of precipitation (rain and melted snow) and 0.2 heavy days. Temperature is set against the county’s own winter trend of +0.4°F per decade since 1951–52.
Flood claims: December–February, from 1978 (— = before the data). The rank compares each winter with all 47 winters from 1978–79 to 2024–25 (#1 is the most claims; no rank is shown for 0 claims). The median winter had 2 claims; 6 of 6 strong winters in the data were above it. Insured exposure grew over time, so counts are not comparable across decades.
Past tendency is not a forecast and not a property-level finding. Before winter: four checks for property teams.
Sources: NOAA county climate records and Pacific climate assessments; FEMA National Flood Insurance Program claims. Method and limits · El Niño 2026–27.
What are the modeled losses by hazard?
From 1991–2000 to 2016–2025, hot days near Maricopa County changed from 127.8 to 140.7 per year. Heavy-rain days changed from 0.0 to 0.0. The table retains humid heat, warm nights and maximum daily rain. Compare the periods alongside the source notes. These decade means describe past conditions; they do not predict a future year or establish a trend.
Maricopa County’s modeled loss across all hazards is $2,195,561,910 per year. The FEMA National Risk Index ranks the hazards below by modeled loss, not rating category.
Show tabular data
| Hazard | Total loss ($/yr) | Of which buildings ($/yr) | Observation window |
|---|---|---|---|
| All hazards (composite) | $2,195,561,910 | $1,201,218,958 | 1996-2023 |
| Riverine flooding | $1,119,501,534 | $1,106,425,058 | 1996-2023 |
| Heat wave | $957,986,784 | Not published | 2005-2024 |
| Wildfire | $42,188,453 | $40,323,983 | 1996-2023 |
| Earthquake | $30,724,390 | $22,473,406 | 1996-2023 |
| Tornado | $5,367,715 | $2,568,299 | 1950-2023 |
| Hurricane | $11,770 | $7,010 | 1851-2024 |
| Coastal flooding | Not available | Not available | 1996-2023 |
These modeled county totals do not estimate property losses, insurance inputs or forecasts. Do not multiply them by location counts.
Reuse this chart
What is exposed in Maricopa County?
Population and asset values show the scale behind county losses. These county totals are exposure measures, not loss figures.
Show tabular data
| Measure | Value | Observation window |
|---|---|---|
| Resident population | 4,418,836 | 2020-2020 |
| Building replacement value | $854,730,526,869 | 2020-2020 |
| Agricultural market value | $1,556,808,461 | 2022-2022 |
What do vulnerability and resilience show?
These relative rankings describe susceptibility to hazard impacts and capacity to recover. They measure no individual asset or outcome.
Show tabular data
| Measure | Score | Observation window |
|---|---|---|
| Social vulnerability index | 27.1 | 2020-2020 |
| Community resilience index | 18.0 | 2020-2020 |
Maricopa County in the state and national rankings
Maricopa County has about $2.20 billion in modeled expected annual loss, ranking #5 of 3,232 nationally. Within Arizona, 61.0% of modeled loss belongs here, placing the county #1 of 15. About $2.20 billion is the modeled yearly average over the long run, rather than a one-year prediction. The next higher national total is about $2.22 billion, in Harris County, TX. The next lower national total is about $2.08 billion, in San Bernardino County, CA. At about $531.4 million, Pima County, AZ is one place lower in the state loss ordering. That puts the estimates about $1.66 billion apart, with 14.8% of state loss in the comparison county.
County hazard loss mix
Riverine Flood leads the modeled expected annual loss mix; bar lengths share a zero baseline.
View chart data
| Hazard | USD / year | Share |
|---|---|---|
| Riverine Flood | 1,119,501,533.89 | 51.0% |
| Heat Wave | 957,986,783.68 | 43.6% |
| Wildfire | 42,188,452.80 | 1.9% |
| Earthquake | 30,724,390.35 | 1.4% |
| Hail | 24,173,608.00 | 1.1% |
| Strong Wind | 8,806,659.96 | 0.4% |
| Other | 12,180,481.37 | 0.6% |
National hazard loss ranks
Riverine Flood ranks #4 of 3,232 by modeled expected annual loss. Higher percentiles mean larger modeled losses.
View chart data
| Hazard | Rank | Percentile |
|---|---|---|
| Riverine Flood | #4 of 3,232 US · #1 of 15 in AZ | 99.91 |
| Heat Wave | #1 of 3,202 US · #1 of 15 in AZ | 100.00 |
| Wildfire | #11 of 3,144 US · #1 of 15 in AZ | 99.68 |
| Earthquake | #96 of 3,232 US · #2 of 15 in AZ | 97.06 |
| Hail | #16 of 3,225 US · #1 of 15 in AZ | 99.53 |
| Strong Wind | #36 of 3,225 US · #1 of 15 in AZ | 98.91 |
Modeled loss per resident
Maricopa has about $497 in modeled expected annual loss per resident. State and US values divide total loss by total population.
View chart data
| Place | USD / resident / year |
|---|---|
| Maricopa | 496.86 |
| Arizona | 503.86 |
| US | 459.35 |
Maricopa County hazard estimates
Riverine Flood
With about $1.12 billion in modeled expected annual loss from riverine flooding, the county ranks #4 of 3,232 in the national comparison. Its 51.0% share of total loss comes with a state loss rank of #1 of 15; FEMA assigns a Very High rating, matching 26 US counties, including 2 in Arizona, for this hazard.
Heat Wave
At about $958.0 million, the modeled expected annual loss from heat waves ranks first among 3,202 US counties. Its 43.6% share of total loss comes with a state loss rank of #1 of 15; FEMA assigns a Very High rating, matching 11 US counties, including 2 in Arizona, for this hazard.
Wildfire
For wildfires, about $42.2 million in expected annual loss puts the county #11 of 3,144 across the US. At 1.9% of the county’s modeled loss, the hazard places #1 of 15 statewide; FEMA assigns a Relatively High rating; the same rating for wildfires covers 11 Arizona counties and 71 across the US.
Earthquake
For earthquakes, about $30.7 million in expected annual loss puts the county #96 of 3,232 across the US. Its 1.4% share of total loss comes with a state loss rank of #2 of 15; FEMA assigns a Relatively Moderate rating, matching 250 US counties, including 3 in Arizona, for this hazard.
Hail
With about $24.2 million in modeled expected annual loss from hail, the county ranks #16 of 3,225 in the national comparison. At 1.1% of the county’s modeled loss, the hazard places #1 of 15 statewide; FEMA assigns a Very High rating; the same rating for hail covers 1 Arizona county and 25 across the US.
Strong Wind
The national loss rank for strong wind is #36 of 3,225, based on about $8.8 million in modeled expected annual loss. This hazard makes up 0.4% of the total; FEMA assigns a Very High rating, and its loss ranks #1 of 15 in Arizona; the same rating for strong wind covers 1 Arizona county and 63 across the US.
For riverine flooding, modeled loss is about $161.5 million above heat waves, leaving 7.4 percentage points between their county shares. The loss estimate for heat waves exceeds wildfires by about $915.8 million, equivalent to 41.7 percentage points of total loss. The loss estimate for wildfires exceeds earthquakes by about $11.5 million, equivalent to 0.5 percentage points of total loss. For earthquakes, modeled loss is about $6.6 million above hail, leaving 0.3 percentage points between their county shares. About $15.4 million separates hail from strong wind in the local estimates, equivalent to 0.7 percentage points of county loss.
Population and recorded values
FEMA counts 4,418,836 residents in Maricopa County, across about 9,319 square miles. About $854.73 billion is the building value amount in FEMA’s record. About $1.56 billion is the agricultural value amount in FEMA’s record. Total modeled loss averages about $497 per resident annually, compared with about $504 statewide. The county holds 61.8% of the state population, compared with 61.0% of modeled loss. The county contains 62.9% of the building value recorded across Arizona. Its population density ranks 1 within 15 Arizona counties that have both area and population estimates. Those recorded totals give about 474 residents per square mile, versus about 62 across Arizona. The median county population in Arizona is about 125,169, compared with 4,418,836 locally. The county’s national shares are 1.3% for population and 1.4% for modeled loss. The county’s about $497 per resident compares with about $459 nationally in modeled annual loss. The six hazards described above together make up 99.4% of modeled loss, about $2.18 billion annually. The balance outside those six estimates is about $12.2 million, or 0.6% of total loss. In position 7 locally, tornadoes has about $5.4 million in modeled annual loss, ranking #1 of 15 statewide. With 0.2% of county loss, this hazard has national placement #438 of 3,225. The county’s number 8 hazard by dollar loss is drought: about $4.6 million, with a state rank of #1 of 15. Nationally, this estimate places #58 of 3,225; its share of the county’s modeled loss is 0.2%.
FEMA labels and risk score
Maricopa County has a FEMA risk index score of about 99.9, ranking #5 of 3,144 nationally. For risk index, FEMA assigns Very High; 1 county in Arizona has that label. The expected annual loss rating is Very High, a label shared by 1 of 15 Arizona counties. For social vulnerability, FEMA assigns Relatively Low; 2 counties in Arizona have that label. For community resilience, FEMA assigns Very Low; 12 counties in Arizona have that label. Its risk score ranks #1 of 15 within Arizona, while its loss total ranks #1 of 15. Within Arizona, 1 counties share both labels: Relatively Low vulnerability and Very Low resilience. Those counties together hold 61.0% of Arizona modeled loss, including this county’s 100.0% share of their total. With a score of about 99.1, Pima County, AZ ranks #2 of 15 statewide, immediately below this county. Its share of statewide modeled loss is 14.8%; FEMA’s risk index label there is Relatively High. Across the US, this social vulnerability category, Relatively Low, covers 30.0% of residents in 632 counties. Across the US, this community resilience category, Very Low, covers 18.6% of residents in 628 counties. Across the county’s hazard ratings, 4 carry Very High: hail, heat waves, riverine flooding, strong wind. The county’s Relatively High group contains 3 hazards: drought, lightning, wildfires. The county’s Relatively Moderate group contains 2 hazards: earthquakes, tornadoes. The local Relatively Low hazard group contains 2 entries: landslides, winter weather. Across the county’s hazard ratings, 2 carry Very Low: avalanches, hurricanes.
What else should I know about Maricopa County?
What does FEMA estimate for riverine flooding in Maricopa County?
For riverine flooding, FEMA lists Maricopa County at Very High, with about $1.12 billion in modeled expected annual loss.
Where does Maricopa County rank within Arizona?
Maricopa County ranks #1 of 15 for modeled expected annual loss.
How large is Maricopa County?
FEMA records about 9,319 square miles for Maricopa County.
Which mitigation plan is listed for Maricopa County?
The plan listed for Maricopa County is Maricopa County Multi-Jurisdictional Hazard Mitigation Plan.
What is the FEMA social vulnerability rating for Maricopa County?
FEMA assigns Maricopa County a Relatively Low social vulnerability rating.
Where does Maricopa County rank nationally by loss?
Maricopa County places #5 of 3,232 for modeled expected annual loss.
What annual loss does FEMA model for Maricopa County?
Maricopa County has about $2.20 billion in modeled expected annual loss, a long-run average rather than a yearly forecast.
Where next for Maricopa County?
See how the county compares across the state in Arizona natural hazard risk by county, download the FEMA county hazard data, or review the county climate risk data API and bulk files. Check the sources and what each measure can show on the methodology page.