Mercer County, NJ
FEMA National Risk Index scores, disaster declarations & hazard data
Mercer County has experienced 28 federally declared disasters since 1965, most recently Remnants Of Hurricane Ida in 2021. Its overall natural hazard risk is rated Relatively High — higher risk than most US counties.
Mercer County's highest-rated hazards are strong wind, winter weather, and inland flooding, with its top risk rated "Very High" by FEMA's National Risk Index. Recorded storm events have increased 26% over the past five years compared to the prior five-year period. Community vulnerability is elevated (74th percentile nationally), suggesting residents may face greater difficulty recovering from major disasters.
Past disasters & FEMA designations
A federal disaster declaration officially designates a county for FEMA disaster assistance. Mercer County has been designated in 28 declarations since 1965, covering 8 disaster types including hurricane (9), severe storm (7), snowstorm (4).
| Year | Type | Event name |
|---|---|---|
| 2021 | Hurricane | Remnants Of Hurricane Ida |
| 2021 | Hurricane | Remnants Of Hurricane Ida |
| 2020 | Biological | Covid-19 Pandemic |
| 2020 | Biological | Covid-19 |
| 2016 | Severe Storm | Severe Winter Storm And Snowstorm |
| 2013 | Hurricane | Hurricane Sandy |
| 2013 | Hurricane | Hurricane Sandy |
| 2012 | Severe Storm | Remnants Of Tropical Storm Lee |
| 2011 | Snowstorm | Severe Winter Storm And Snowstorm |
| 2011 | Hurricane | Hurricane Irene |
Showing the 10 most recent of 28 total declarations since 1965.
Source: FEMA OpenFEMA Disaster Declarations Summaries. A single disaster can produce more than one record per county. Data current through September 2026.
Risk by hazard type
| Hazard | Risk rating | Risk score | Recorded events | Deaths | Prop. damage |
|---|---|---|---|---|---|
| Wildfire | Relatively Low | 73.4 | 0 | 0 | — |
| Inland Flooding | Relatively High | 97.2 | 36 | 2 | $53.0M |
| Coastal Flooding | Relatively Low | 56.8 | 10 | 0 | — |
| Earthquake | Relatively Moderate | 94 | — | — | — |
| Heat Wave | Relatively Moderate | 95.8 | 10 | 0 | — |
| Tornado | Relatively Moderate | 81.9 | 8 | 0 | — |
| Hurricane | Relatively High | 94.6 | 0 | 0 | — |
| Hail | Very Low | 29.5 | 23 | 0 | — |
| Strong Wind | Very High | 99.5 | 0 | 0 | — |
| Winter Weather | Very High | 97.7 | 0 | 0 | — |
| Ice Storm | Very High | 96.3 | — | — | — |
| Cold Wave | Relatively Moderate | 85.2 | — | — | — |
| Lightning | Relatively High | 93.5 | 1 | 0 | — |
| Drought | Relatively Low | 62.1 | 0 | 0 | — |
| Landslide | Very Low | 53.5 | 0 | 0 | — |
| Avalanche | Not Applicable | — | — | — | — |
| Tsunami | Not Applicable | — | — | — | — |
| Volcanic Activity | Not Applicable | — | — | — | — |
Scores are 0–100 percentiles relative to all US counties — higher means more exposed, not that a disaster is likely this year. Event counts: NOAA Storm Events 2016–2026; earthquake counts from USGS ComCat (M3.0+, 1996–2026). See the methodology page for details.
Community vulnerability
Mercer County ranks in the 74th percentile (Moderate) for community vulnerability — a measure of how hard disaster impacts tend to hit residents. Higher vulnerability means more displacement, worse health outcomes, and slower recovery after a disaster.
| SVI theme | Percentile | Vulnerability level |
|---|---|---|
| Overall | 74th | Moderate |
| Socioeconomic status | 56th | Moderate |
| Household characteristics | 41st | Low |
| Racial & ethnic minority status | 89th | High |
| Housing type & transportation | 94th | High |
Source: CDC/ATSDR Social Vulnerability Index 2022. Percentiles compare counties nationally — higher means more vulnerable relative to other counties. See CDC SVI for full methodology.
Future risk outlook
| Wildfire metric | National percentile | Level |
|---|---|---|
| Burn probability | 35th | Relatively Low |
| Risk to homes | 35th | Relatively Low |
| Buildings in direct exposure zone | 35.0% | — |
NOAA tracked 88 weather events in this county over 2016–2025: 39 in 2016–20 vs 49 in 2021–25 (+26% — frequency increasing).
Wildfire: USDA Forest Service Wildfire Risk to Communities (RDS-2020-0016-2) — modeled values, not annual forecasts. See wildfirerisk.org. Inland flood and heat projections pending data availability; coastal sea-level projections are available for select coastal counties below — see the data page.
Nearby counties
Frequently asked questions
What natural hazards pose the greatest risk in Mercer County?
According to the FEMA National Risk Index, the highest-risk hazards in Mercer County, New Jersey are strong wind, winter weather, and inland flooding. The county's overall natural hazard risk is rated Relatively High — higher risk than most US counties.
Has Mercer County received federal disaster declarations?
Yes. Mercer County has received 28 federal disaster declarations since 1965, including declarations in 2021. The most common disaster type on record is hurricane (9 declarations).
Has Mercer County had any FEMA disaster declarations in 2024, 2025, or 2026?
No federal disaster declarations have been recorded for Mercer County since the start of 2024. Its most recent declaration on record is Remnants Of Hurricane Ida in 2021.
How does Mercer County's natural hazard risk compare to nearby counties?
Among neighboring counties, Middlesex County, NJ has the highest overall natural hazard risk (Relatively High) and Hunterdon County, NJ has the lowest (Relatively Low). Mercer County is rated Relatively High overall.
How is Mercer County's composite disaster risk index calculated?
Mercer County's composite disaster risk index — officially FEMA's National Risk Index (NRI) — scores every US county on a 0–100 percentile scale across 18 natural hazard types, factoring in expected annual loss, social vulnerability, and community resilience. Mercer County's composite score of 95 means its overall natural hazard risk is higher than 95% of US counties.