Delaware County, Iowa Natural Disaster Risk
FEMA National Risk Index assessment · IA
LowComposite Risk Score
National percentile: 50th
Delaware County faces low composite natural disaster risk (NRI Risk Index score 49.7, 50th national percentile), driven primarily by hail and drought exposure. Expected annual loss across all 18 hazard types is $17M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
Overall natural disaster risk in Delaware County is low, with a National Risk Index score of 49.7 out of 100 — placing it in the 50th national percentile and below the national average for natural-disaster risk. The score blends Expected Annual Loss, Social Vulnerability, and Community Resilience across all 18 FEMA hazard types.
Risk here concentrates in hail (ice stones from severe thunderstorms that damage property and crops) at Medium risk — $1M in expected annual loss and about 4.51 events per year; drought (extended dry periods that stress water supplies and agriculture) at Medium risk — $1M in expected annual loss and about 11.20 events per year; and strong wind (damaging straight-line winds outside of tornadoes and hurricanes) at Medium risk — $1M in expected annual loss and about 5.40 events per year. Across all hazards, FEMA estimates $17M in expected annual loss for a population of 17K.
Beyond physical exposure, Delaware County has a low social vulnerability rating (how susceptible the population is to harm) and a very high community resilience rating (its capacity to prepare for and recover from disasters). A less vulnerable population paired with strong resilience helps the community absorb and recover from events.
History supports the rating: Delaware County has received 18 federal disaster declarations since 1968, including 8 for flood events and 7 for severe storm events. The most recent was Covid-19 Pandemic (biological), declared in March 2020.
Among 99 Iowa counties, Delaware County ranks #26 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Hail | Medium | 4.51 / yr | $1M |
| Drought | Medium | 11.20 / yr | $1M |
| Strong Wind | Medium | 5.40 / yr | $1M |
| Landslide | Low | 0.11 / yr | $5K |
| Riverine Flood | Low | 1.21 / yr | $10M |
| Tornado | Low | 0.49 / yr | $2M |
| Cold Wave | Low | 8.11 / yr | $1M |
| Winter Weather | Low | 16.89 / yr | $53K |
| Heat Wave | Very Low | 4.68 / yr | $179K |
| Ice Storm | Low | 0.24 / yr | $31K |
| Lightning | Low | 40.48 / yr | $107K |
| Earthquake | Very Low | 0.00 / yr | $46K |
| Hurricane | Very Low | 0.01 / yr | $6K |
| Wildfire | Very Low | 0.00 / yr | $4K |
| Avalanche | Very Low | 0.00 / yr | $0 |
| Coastal Flood | Very Low | 0.00 / yr | $0 |
| Tsunami | Very Low | 0.00 / yr | $0 |
| Volcanic Activity | Very Low | 0.00 / yr | $0 |
Disaster History
Delaware County has received 18 federal disaster declarations since 1968, most recently Covid-19 Pandemic in March 2020. Most frequent causes: Flood (8), Severe Storm (7), Biological (2).
| Declared | Type | Disaster |
|---|---|---|
| March 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| August 2018 | Severe Storm | Severe Storms, Tornadoes, Straight-Line Winds, and Flooding |
| October 2016 | Flood | Severe Storms and Flooding |
| July 2013 | Severe Storm | Severe Storms, Tornadoes, and Flooding |
| July 2013 | Severe Storm | Severe Storms, Tornadoes, and Flooding |
| July 2010 | Severe Storm | Severe Storms, Flooding, and Tornadoes |
| May 2008 | Severe Storm | Severe Storms, Tornadoes, and Flooding |
| September 2005 | Hurricane | Hurricane Katrina Evacuation |
| May 2004 | Severe Storm | Severe Storms, Tornadoes, and Flooding |
Showing the 10 most recent of 18 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Delaware County?
Delaware County has a composite FEMA National Risk Index score of 49.7 out of 100, placing it in the Low category and the 50th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Delaware County?
The three highest-rated hazards are Hail (Medium, $1M EAL), Drought (Medium, $1M EAL), Strong Wind (Medium, $1M EAL). These account for most of the county's expected annual losses.
How does Delaware County compare to other Iowa counties?
Delaware County ranks #26 of 99 Iowa counties for overall natural disaster risk, with a low rating.
How many federally declared disasters has Delaware County had?
FEMA records 18 federal disaster declarations for Delaware County since 1968, most often 8 for flood events and 7 for severe storm events. The most recent was Covid-19 Pandemic, declared in March 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. Delaware County's $17M EAL is a statistical average, not a guarantee for any specific year or address.