Arizona inland flooding risk
Maricopa County has the highest inland flooding risk in Arizona, scoring 99.9 out of 100 — rated "Very High" by FEMA's National Risk Index. Recorded inland flooding events across Arizona have increased 79% over the past five years compared to the prior five-year period.
| # | County | NRI score | Rating |
NOAA events 2016–2026 |
|---|---|---|---|---|
| 1 | Maricopa County | 99.9 | Very High | 505 |
| 2 | Pima County | 99.5 | Very High | 202 |
| 3 | Mohave County | 97.1 | Relatively High | 404 |
| 4 | Coconino County | 96.5 | Relatively High | 171 |
| 5 | Pinal County | 96.4 | Relatively High | 94 |
| 6 | Yavapai County | 96.1 | Relatively High | 244 |
| 7 | Cochise County | 93.8 | Relatively High | 83 |
| 8 | Gila County | 93.1 | Relatively Moderate | 176 |
| 9 | La Paz County | 91.5 | Relatively Moderate | 88 |
| 10 | Yuma County | 91 | Relatively Moderate | 53 |
| 11 | Navajo County | 89.5 | Relatively Moderate | 59 |
| 12 | Santa Cruz County | 87.4 | Relatively Moderate | 32 |
| 13 | Apache County | 80.7 | Relatively Moderate | 42 |
| 14 | Graham County | 67.9 | Relatively Low | 24 |
| 15 | Greenlee County | 29.6 | Very Low | 3 |
Source: FEMA National Risk Index v1.20.0, December 2025. Scores are 0–100 percentile rankings among all US counties. See the methodology page for definitions. Download the full CSV for all counties.
Inland Flooding risk nationally:
Other hazard risks in Arizona:
Frequently asked questions
What is the highest inland flooding risk county in Arizona?
Maricopa County, AZ has the highest inland flooding risk in Arizona, with a FEMA National Risk Index score of 99.9 out of 100 (rated "Very High").
How many counties in Arizona are rated Very High for inland flooding risk?
2 of 15 scored Arizona counties are rated "Very High" for inland flooding risk by FEMA's National Risk Index.
What causes inland flooding risk in Arizona?
Inland flooding covers riverine and surface (pluvial) flooding — the most common and costly natural disaster type in the US. High scores appear across river floodplains in the Midwest, South, and Mid-Atlantic, where legacy development in flood-prone areas and aging stormwater infrastructure concentrate risk.