Merrimack County, NH
FEMA National Risk Index scores, disaster declarations & hazard data
Merrimack County has experienced 29 federally declared disasters since 1973, most recently Covid-19 in 2020. Its overall natural hazard risk is rated Relatively Low — lower risk than most US counties.
Merrimack County's highest-rated hazards are ice storm, lightning, and inland flooding, with its top risk rated "Relatively High" by FEMA's National Risk Index. Recorded storm events have increased 84% over the past five years compared to the prior five-year period. Community vulnerability is relatively low (21st percentile nationally), indicating stronger recovery capacity than most US counties.
Past disasters & FEMA designations
A federal disaster declaration officially designates a county for FEMA disaster assistance. Merrimack County has been designated in 29 declarations since 1973, covering 6 disaster types including severe storm (12), snowstorm (5), flood (5).
| Year | Type | Event name |
|---|---|---|
| 2020 | Biological | Covid-19 Pandemic |
| 2020 | Biological | Covid-19 |
| 2018 | Severe Storm | Severe Storm And Flooding |
| 2013 | Severe Storm | Severe Winter Storm And Snowstorm |
| 2013 | Hurricane | Hurricane Sandy |
| 2012 | Severe Storm | Severe Storm |
| 2011 | Hurricane | Tropical Storm Irene |
| 2011 | Hurricane | Hurricane Irene |
| 2010 | Severe Storm | Severe Winter Storm |
| 2009 | Severe Storm | Severe Winter Storm |
Showing the 10 most recent of 29 total declarations since 1973.
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 | Very Low | 35.2 | 0 | 0 | — |
| Inland Flooding | Relatively Moderate | 85.8 | 40 | 0 | $115K |
| Coastal Flooding | Not Applicable | — | 0 | 0 | — |
| Earthquake | Relatively Low | 76.1 | 1 | — | — |
| Heat Wave | Relatively Low | 70.6 | 1 | 0 | — |
| Tornado | Relatively Low | 56.2 | 1 | 0 | — |
| Hurricane | Relatively Moderate | 84.8 | 0 | 0 | — |
| Hail | Relatively Low | 37.2 | 27 | 0 | $100 |
| Strong Wind | Relatively Moderate | 52.5 | 0 | 0 | — |
| Winter Weather | Relatively Moderate | 80.4 | 0 | 0 | — |
| Ice Storm | Relatively High | 89.8 | — | — | — |
| Cold Wave | Relatively Low | 53.8 | — | — | — |
| Lightning | Relatively High | 89.2 | 2 | 0 | — |
| Drought | Relatively Low | 58.8 | 0 | 0 | — |
| Landslide | Relatively Low | 81.1 | 0 | 0 | — |
| Avalanche | Very Low | 28.5 | — | — | — |
| 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
Merrimack County ranks in the 21st percentile (Very low) 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 | 21st | Very low |
| Socioeconomic status | 16th | Very low |
| Household characteristics | 8th | Very low |
| Racial & ethnic minority status | 24th | Very low |
| Housing type & transportation | 67th | Moderate |
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 | 11th | Very Low |
| Risk to homes | 12th | Very Low |
| Buildings in direct exposure zone | 69.5% | — |
NOAA tracked 71 weather events in this county over 2016–2025: 25 in 2016–20 vs 46 in 2021–25 (+84% — 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 Merrimack County?
According to the FEMA National Risk Index, the highest-risk hazards in Merrimack County, New Hampshire are ice storm, lightning, and inland flooding. The county's overall natural hazard risk is rated Relatively Low — lower risk than most US counties.
Has Merrimack County received federal disaster declarations?
Yes. Merrimack County has received 29 federal disaster declarations since 1973, including declarations in 2020. The most common disaster type on record is severe storm (12 declarations).
Has Merrimack County had any FEMA disaster declarations in 2024, 2025, or 2026?
No federal disaster declarations have been recorded for Merrimack County since the start of 2024. Its most recent declaration on record is Covid-19 in 2020.
How does Merrimack County's natural hazard risk compare to nearby counties?
Among neighboring counties, Hillsborough County, NH has the highest overall natural hazard risk (Relatively Moderate) and Sullivan County, NH has the lowest (Very Low). Merrimack County is rated Relatively Low overall.
How is Merrimack County's composite disaster risk index calculated?
Merrimack 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. Merrimack County's composite score of 78 means its overall natural hazard risk is higher than 78% of US counties.