Ontario County, New York: Natural Disaster Risk and History
Ontario County, New York has a Relatively Low natural-hazard risk rating in FEMA's National Risk Index (v1.20, December 2025): a score of 63.5 out of 100, higher than about 63% of US counties, with inland (river and flash) flooding, ice storms and strong winds scoring highest of its 18 hazards and $27 million a year in expected losses.
OpenFEMA lists 18 federal disaster declarations that included Ontario County since 1972, not counting 2 for COVID-19; the latest is DR-4825-NY (Remnants of Tropical Storm Debby, declared 24 September 2024). NOAA's Storm Prediction Center recorded 7 tornadoes touching Ontario County from 1950 to 2025.
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Population 112,342 Buildings worth $29 billion Area 669 sq mi Risk rank in New York 39 of 62 FIPS 36069
All 18 hazards, highest risk first
FEMA National Risk Index| Hazard | Risk rating | Score | Expected loss a year | How often | Events in record |
|---|---|---|---|---|---|
| Inland flooding | Relatively Moderate | 78.8 | $21 million | about 1.4 a year | 38 |
| Ice storm | Relatively Moderate | 77.1 | $379,454 | about once every 1.1 years | 64 |
| Strong wind | Relatively Moderate | 76.4 | $1.3 million | about 1.5 a year | 56 |
| Drought | Relatively Moderate | 75.7 | $818,254 | about 2.6 a year | 70 |
| Hurricane | Relatively Low | 58.9 | $211,359 | about once every 37 years | 10 |
| Hail | Relatively Low | 57.3 | $394,415 | about 1.5 a year | 57 |
| Lightning | Relatively Low | 55.8 | $325,764 | about 3 a year | 97,314 strikes |
| Landslide | Very Low | 54.9 | $2,158 | about once every 4.2 years | — |
| Earthquake | Very Low | 53.1 | $366,397 | rarer than once in 1,000 years | — |
| Heat wave | Relatively Low | 47.0 | $369,002 | about 3.4 a year | 61 |
| Tornado | Relatively Low | 44.0 | $1.2 million | about once every 12 years | 5 |
| Avalanche | Very Low | 43.9 | $388 | about once every 100 years | 0 |
| Wildfire | Very Low | 38.3 | $26,363 | rarer than once in 1,000 years | — |
| Winter weather | Very Low | 18.8 | $18,507 | about 16 a year | 300 |
| Cold wave | Very Low | 12.5 | $131,466 | about 3.1 a year | 59 |
| Coastal flooding | Not Applicable | — | — | — | — |
| Tsunami | Not Applicable | — | — | — | — |
| Volcanic activity | Not Applicable | — | — | — | — |
Score: FEMA's percentile among US counties that face the hazard (higher = more risk). Expected loss: FEMA's modelled average yearly loss to buildings, people (as a statistical value) and crops. How often: FEMA's annualised frequency of the hazard in the county; for some hazards it counts event-days, so it is a rough guide, not a forecast. "Not Applicable" means FEMA does not model that hazard here.
Federal disaster declarations 18
Most common: Severe Storm 5, Flood 3, Snowstorm 3, Hurricane 2.
| Decade | Declarations | Incident types |
|---|---|---|
| 1970s | 1 | Flood |
| 1990s | 5 | Snowstorm ×3, Severe Storm, Flood |
| 2000s | 7 | Severe Storm ×2, Other ×2, Hurricane, Severe Ice Storm, Fire |
| 2010s | 3 | Severe Storm, Hurricane, Flood |
| 2020s | 2 | Tropical Storm, Severe Storm |
The last 10
Widest declarations that included Ontario County
- Hurricane Sandy (2012, EM-3351-NY): 62 New York counties designated.
- Hurricane Katrina Evacuation (2005, EM-3262-NY): 62 New York counties designated.
- Severe Storms and Flooding (2004, DR-1534-NY): 62 New York counties designated.
Named storms in its declarations: Tropical Storm Debby (2024), Hurricane Sandy (2012), Hurricane Katrina (2005), Tropical Storm Agnes (1972).
Not counted above: 2 COVID-19 ("Biological") declarations — in 2020 every US county was included. New York also had 7 statewide declarations with no county list.
Tornado record since 1950 7
| Tornadoes touching the county | 7 |
|---|---|
| Strongest-rated | (E)F2 ×1 |
| Peak month | July (3) |
| Deadliest | — |
| Longest path | 29 Aug 2009, EF0, 10.6 mi path |
| Most recent | 7 Jul 2025, EF2, 1.7 mi path |
| Deaths / injuries on those paths | 0 / 0 |
| Rating | (E)F0 | (E)F1 | (E)F2 | (E)F3 | (E)F4 | (E)F5 | Unrated |
|---|---|---|---|---|---|---|---|
| Count | 3 | 3 | 1 | 0 | 0 | 0 | 0 |
| Decade | 1950s | 1960s | 1970s | 1980s | 1990s | 2000s | 2010s | 2020s |
|---|---|---|---|---|---|---|---|---|
| Count | 0 | 0 | 0 | 0 | 3 | 1 | 1 | 2 |
Deaths and injuries are for each tornado's whole path, which can run beyond this county. F-scale ratings before February 2007, Enhanced Fujita (EF) after.
How Ontario County compares with its 5 nearest counties
| County | Distance | Overall risk | Score | Top hazard |
|---|---|---|---|---|
| Ontario County (this page) | — | Relatively Low | 63.5 | Inland flooding |
| Yates County | 29 km | Relatively Low | 46.6 | Drought |
| Seneca County | 40 km | Very Low | 41.8 | Drought |
| Wayne County | 40 km | Relatively Low | 56.3 | Hail |
| Livingston County | 41 km | Relatively Low | 56.4 | Inland flooding |
| Monroe County | 46 km | Relatively Moderate | 93.8 | Cold wave |
Nearest by distance between county centres. Every county in New York, ranked.
Vulnerability and resilience
| Social vulnerability | Relatively Low 24.1 |
|---|---|
| Community resilience | Very High 94.9 |
| Community risk factor | 0.92 |
| Expected annual loss, all hazards | $27 million |
FEMA scales expected losses up where social vulnerability is high (people who may find it harder to prepare, evacuate or recover) and down where community resilience is high. A factor above 1 raises the risk score. For social vulnerability a high rating is worse; for resilience a high rating is better.
Prepare for Ontario County's main hazards
- Right now: National Weather Service alerts for New York · all official warnings on Global Incident Tracker.
- Inland flooding: Flood safety: why shallow water kills · Floods recorded
- Ice storm: Power outages now · Carbon monoxide in winter
- Strong wind: Power outages now
- Your property's flood zone: FEMA Flood Map Service Center ↗ — this page cannot tell you that.
- Official preparedness guidance: Ready.gov ↗ and your county emergency management office.
What this page shows, and what it misses
FEMA's National Risk Index rates a whole county against every other US county; it is a planning-level estimate for nationwide comparison, not a flood-zone map and not a substitute for a local risk assessment or the risk to one home. Declarations are presidential disaster, emergency and fire management declarations that named this county; state declarations and SBA or USDA designations are not included. Tornadoes are counted when the county is one of up to four listed on the track; 670 tornadoes that crossed a state line carry no county list in NOAA's file and are left out.
Federal Emergency Management Agency (FEMA), National Risk Index Dataset: National Risk Index Counties - v1.20.0 (December 2025). Retrieved from https://services.arcgis.com/XG15cJAlne2vxtgt/ArcGIS/rest/services/National_Risk_Index_Counties/FeatureServer/0/query on November 2, 2026, 1:20 PM EST. This product uses the Federal Emergency Management Agency’s National Risk Index dataset API or downloadable datasets but is not endorsed by FEMA. The Federal Government or FEMA cannot vouch for the data or analyses derived from these data after the data have been retrieved from the Agency's website(s).
Federal Emergency Management Agency (FEMA), OpenFEMA Dataset: Disaster Declarations Summaries - v2, retrieved from https://www.fema.gov/api/open/v2/DisasterDeclarationsSummaries on November 2, 2026, 1:21 PM EST. This product uses the Federal Emergency Management Agency's OpenFEMA API, but is not endorsed by FEMA. The Federal Government or FEMA cannot vouch for the data or analyses derived from these data after the data have been retrieved from the Agency's website(s).
Tornado records: NOAA/NWS Storm Prediction Center, Severe Weather Database, tornadoes 1950–2025 (https://www.spc.noaa.gov/wcm/data/1950-2025_actual_tornadoes.csv, downloaded 2 November 2026). Public domain; not endorsed by NOAA. Compiled by Global Incident Tracker.
Questions about Ontario County
What natural disasters is Ontario County, New York most at risk from?
Ontario County, New York has a Relatively Low natural-hazard risk rating in FEMA's National Risk Index (v1.20, December 2025): a score of 63.5 out of 100, higher than about 63% of US counties, with inland (river and flash) flooding, ice storms and strong winds scoring highest of its 18 hazards and $27 million a year in expected losses.
How many federal disaster declarations has Ontario County had?
OpenFEMA lists 18 federal disaster declarations that included Ontario County since 1972, not counting 2 for COVID-19; the latest is DR-4825-NY (Remnants of Tropical Storm Debby, declared 24 September 2024). Another 7 New York declarations were made statewide without a county list.
How many tornadoes have hit Ontario County?
NOAA's Storm Prediction Center recorded 7 tornadoes touching Ontario County from 1950 to 2025.
Is the National Risk Index a flood zone map?
No. The National Risk Index is a planning-level estimate for a whole county, built for nationwide comparison. It does not tell you the flood zone or the risk of a single property: for that, look up the address on FEMA's Flood Map Service Center (msc.fema.gov) and ask your local floodplain manager.