Iowa inland flooding risk
Polk County has the highest inland flooding risk in Iowa, scoring 92.1 out of 100 — rated "Relatively Moderate" by FEMA's National Risk Index. Recorded inland flooding events across Iowa have decreased 67% over the past five years compared to the prior five-year period.
| # | County | NRI score | Rating |
NOAA events 2016–2026 |
|---|---|---|---|---|
| 1 | Polk County | 92.1 | Relatively Moderate | 79 |
| 2 | Scott County | 88.4 | Relatively Moderate | 34 |
| 3 | Linn County | 86.7 | Relatively Moderate | 22 |
| 4 | Johnson County | 79.8 | Relatively Moderate | 20 |
| 5 | Woodbury County | 78.2 | Relatively Moderate | 31 |
| 6 | Black Hawk County | 76.6 | Relatively Moderate | 72 |
| 7 | Pottawattamie County | 74.6 | Relatively Moderate | 17 |
| 8 | Lee County | 70.4 | Relatively Low | 23 |
| 9 | Wapello County | 69.3 | Relatively Low | 18 |
| 10 | Story County | 69.1 | Relatively Low | 40 |
| 11 | Cerro Gordo County | 69 | Relatively Low | 25 |
| 12 | Clinton County | 66.9 | Relatively Low | 29 |
| 13 | Dubuque County | 65.4 | Relatively Low | 36 |
| 14 | Marshall County | 63.1 | Relatively Low | 12 |
| 15 | Muscatine County | 62.6 | Relatively Low | 25 |
| 16 | Delaware County | 61.7 | Relatively Low | 6 |
| 17 | Dallas County | 60.4 | Relatively Low | 22 |
| 18 | Fayette County | 59.2 | Relatively Low | 29 |
| 19 | Clayton County | 58 | Relatively Low | 93 |
| 20 | Floyd County | 56.3 | Relatively Low | 27 |
| 21 | Crawford County | 56.1 | Relatively Low | 3 |
| 22 | Des Moines County | 56 | Relatively Low | 36 |
| 23 | Clay County | 53.8 | Relatively Low | 127 |
| 24 | Hardin County | 52.9 | Relatively Low | 4 |
| 25 | Allamakee County | 50.5 | Relatively Low | 31 |
| 26 | Dickinson County | 49.9 | Relatively Low | 71 |
| 27 | Sioux County | 49.5 | Relatively Low | 101 |
| 28 | Washington County | 48.4 | Relatively Low | 9 |
| 29 | Winneshiek County | 47.5 | Relatively Low | 34 |
| 30 | Webster County | 47.1 | Relatively Low | 38 |
| 31 | Jones County | 46.4 | Relatively Low | 4 |
| 32 | Plymouth County | 45.2 | Relatively Low | 79 |
| 33 | Cass County | 43.4 | Relatively Low | 7 |
| 34 | Jackson County | 43.3 | Relatively Low | 12 |
| 35 | Tama County | 42.4 | Relatively Low | 24 |
| 36 | Marion County | 41.2 | Relatively Low | 9 |
| 37 | Hamilton County | 41 | Relatively Low | 6 |
| 38 | Van Buren County | 40.8 | Relatively Low | 7 |
| 39 | Benton County | 40.3 | Relatively Low | 12 |
| 40 | Jasper County | 40.2 | Relatively Low | 12 |
| 41 | Chickasaw County | 39.6 | Relatively Low | 21 |
| 42 | Cherokee County | 39.1 | Relatively Low | 21 |
| 43 | Buchanan County | 38.6 | Relatively Low | 18 |
| 44 | Carroll County | 37.5 | Relatively Low | 3 |
| 45 | Butler County | 37.2 | Relatively Low | 39 |
| 46 | Harrison County | 37 | Relatively Low | 8 |
| 47 | Madison County | 36.6 | Relatively Low | 5 |
| 48 | Mahaska County | 36.4 | Relatively Low | 18 |
| 49 | Mitchell County | 36.2 | Relatively Low | 18 |
| 50 | Warren County | 35.9 | Relatively Low | 13 |
| 51 | Wright County | 35.1 | Relatively Low | 13 |
| 52 | Montgomery County | 34.6 | Very Low | 3 |
| 53 | Bremer County | 33.4 | Very Low | 21 |
| 54 | Buena Vista County | 32.9 | Very Low | 26 |
| 55 | Davis County | 32.7 | Very Low | 3 |
| 56 | Iowa County | 32.6 | Very Low | 12 |
| 57 | Union County | 30.1 | Very Low | 2 |
| 58 | Appanoose County | 30 | Very Low | 8 |
| 59 | Keokuk County | 29.6 | Very Low | 5 |
| 60 | Boone County | 28.8 | Very Low | 13 |
| 61 | Cedar County | 27.6 | Very Low | 5 |
| 62 | Page County | 27.5 | Very Low | 1 |
| 63 | Mills County | 27.4 | Very Low | 9 |
| 64 | Henry County | 26.7 | Very Low | 3 |
| 65 | Kossuth County | 26.7 | Very Low | 23 |
| 66 | Winnebago County | 25.6 | Very Low | 1 |
| 67 | Howard County | 25.4 | Very Low | 10 |
| 68 | Monona County | 25 | Very Low | 6 |
| 69 | Adair County | 23.8 | Very Low | 3 |
| 70 | Lucas County | 22.7 | Very Low | 5 |
| 71 | Guthrie County | 22 | Very Low | 4 |
| 72 | Hancock County | 21.6 | Very Low | 6 |
| 73 | Louisa County | 20.9 | Very Low | 25 |
| 74 | Taylor County | 20.9 | Very Low | 2 |
| 75 | Calhoun County | 20.6 | Very Low | 3 |
| 76 | Emmet County | 20.4 | Very Low | 28 |
| 77 | Jefferson County | 20.4 | Very Low | 6 |
| 78 | Poweshiek County | 20.3 | Very Low | 9 |
| 79 | Audubon County | 19.8 | Very Low | 2 |
| 80 | Lyon County | 19.6 | Very Low | 62 |
| 81 | Shelby County | 19.5 | Very Low | 0 |
| 82 | Humboldt County | 18.9 | Very Low | 22 |
| 83 | O'Brien County | 18.5 | Very Low | 55 |
| 84 | Fremont County | 18.4 | Very Low | 15 |
| 85 | Ida County | 18.4 | Very Low | 8 |
| 86 | Pocahontas County | 18.1 | Very Low | 3 |
| 87 | Sac County | 17.2 | Very Low | 4 |
| 88 | Decatur County | 15.8 | Very Low | 5 |
| 89 | Osceola County | 14.9 | Very Low | 4 |
| 90 | Grundy County | 14.2 | Very Low | 7 |
| 91 | Franklin County | 14 | Very Low | 13 |
| 92 | Wayne County | 14 | Very Low | 2 |
| 93 | Greene County | 12 | Very Low | 3 |
| 94 | Adams County | 11.5 | Very Low | 3 |
| 95 | Worth County | 10.7 | Very Low | 7 |
| 96 | Clarke County | 9.6 | Very Low | 3 |
| 97 | Monroe County | 9.1 | Very Low | 8 |
| 98 | Palo Alto County | 9 | Very Low | 18 |
| 99 | Ringgold County | 5 | 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 Iowa:
Frequently asked questions
What is the highest inland flooding risk county in Iowa?
Polk County, IA has the highest inland flooding risk in Iowa, with a FEMA National Risk Index score of 92.1 out of 100 (rated "Relatively Moderate").
What causes inland flooding risk in Iowa?
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.