Ontario County, New York Natural Disaster Risk
FEMA National Risk Index assessment · NY
LowComposite Risk Score
National percentile: 64th
Ontario County faces low composite natural disaster risk (NRI Risk Index score 63.5, 64th national percentile), driven primarily by riverine flood and ice storm exposure. Expected annual loss across all 18 hazard types is $27M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
Ontario County carries a low composite natural disaster risk, with a National Risk Index score of 63.5 out of 100 — placing it in the 64th 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.
The county's risk is driven primarily by riverine flood (rivers and streams overflowing their banks after heavy rain or snowmelt) at Medium risk — $21M in expected annual loss and about 1.36 events per year; ice storm (freezing rain that coats surfaces in heavy, damaging ice) at Medium risk — $379K in expected annual loss and about 0.94 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 1.47 events per year. Across all hazards, FEMA estimates $27M in expected annual loss for a population of 112K.
Beyond physical exposure, Ontario 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.
The federal record bears this out: Ontario County has received 20 federal disaster declarations since 1972, including 5 for severe storm events and 3 for flood events. The most recent was Remnants of Tropical Storm Debby (tropical storm), declared in September 2024.
Among 62 New York counties, Ontario County ranks #39 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Riverine Flood | Medium | 1.36 / yr | $21M |
| Ice Storm | Medium | 0.94 / yr | $379K |
| Strong Wind | Medium | 1.47 / yr | $1M |
| Drought | Medium | 2.55 / yr | $818K |
| Hurricane | Low | 0.03 / yr | $211K |
| Hail | Low | 1.51 / yr | $394K |
| Lightning | Low | 29.75 / yr | $326K |
| Landslide | Very Low | 0.24 / yr | $2K |
| Earthquake | Very Low | 0.00 / yr | $366K |
| Heat Wave | Low | 3.42 / yr | $369K |
| Tornado | Low | 0.09 / yr | $1M |
| Avalanche | Very Low | 0.01 / yr | $388 |
| Wildfire | Very Low | 0.00 / yr | $26K |
| Winter Weather | Very Low | 15.79 / yr | $19K |
| Cold Wave | Very Low | 3.11 / yr | $131K |
| 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
Ontario County has received 20 federal disaster declarations since 1972, most recently Remnants of Tropical Storm Debby in September 2024. Most frequent causes: Severe Storm (5), Flood (3), Snowstorm (3).
| Declared | Type | Disaster |
|---|---|---|
| September 2024 | Tropical Storm | Remnants of Tropical Storm Debby |
| July 2023 | Severe Storm | Severe Storms and Flooding |
| March 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| July 2014 | Severe Storm | Severe Storms and Flooding |
| October 2012 | Hurricane | Hurricane Sandy |
| June 2011 | Flood | Severe Storms, Flooding, Tornadoes, and Straight-Line Winds |
| September 2005 | Hurricane | Hurricane Katrina Evacuation |
| August 2004 | Severe Storm | Severe Storms and Flooding |
| August 2003 | Severe Storm | Severe Storms, Flooding, and Tornadoes |
Showing the 10 most recent of 20 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Ontario County?
Ontario County has a composite FEMA National Risk Index score of 63.5 out of 100, placing it in the Low category and the 64th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Ontario County?
The three highest-rated hazards are Riverine Flood (Medium, $21M EAL), Ice Storm (Medium, $379K EAL), Strong Wind (Medium, $1M EAL). These account for most of the county's expected annual losses.
How does Ontario County compare to other New York counties?
Ontario County ranks #39 of 62 New York counties for overall natural disaster risk, with a low rating.
How many federally declared disasters has Ontario County had?
FEMA records 20 federal disaster declarations for Ontario County since 1972, most often 5 for severe storm events and 3 for flood events. The most recent was Remnants of Tropical Storm Debby, declared in September 2024.
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. Ontario County's $27M EAL is a statistical average, not a guarantee for any specific year or address.