Merrimack County
New Hampshire — Natural Disaster Risk Assessment
LowComposite Risk Score
National percentile: 78th
Merrimack County faces low composite natural disaster risk (NRI Risk Index score 78.2, 78th national percentile), driven primarily by ice storm and lightning exposure. Expected annual loss across all 18 hazard types is $49M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Top Hazards
All 18 Hazard Risks
| Ice Storm | High | 1.84 / yr | $1M |
| Lightning | High | 20.57 / yr | $1M |
| Riverine Flood | Medium | 2.61 / yr | $34M |
| Hurricane | Medium | 0.09 / yr | $4M |
| Landslide | Low | 1.29 / yr | $23K |
| Winter Weather | Medium | 19.13 / yr | $268K |
| Earthquake | Low | 0.00 / yr | $2M |
| Heat Wave | Low | 3.42 / yr | $1M |
| Drought | Low | 2.15 / yr | $329K |
| Tornado | Low | 0.13 / yr | $2M |
| Cold Wave | Low | 1.74 / yr | $1M |
| Strong Wind | Medium | 0.91 / yr | $748K |
| Hail | Low | 2.12 / yr | $202K |
| Wildfire | Very Low | 0.00 / yr | $24K |
| Avalanche | Very Low | 0.01 / yr | $119 |
| Coastal Flood | Very Low | 0.00 / yr | $0 |
| Tsunami | Very Low | 0.00 / yr | $0 |
| Volcanic Activity | Very Low | 0.00 / yr | $0 |
Frequently Asked Questions
What is the overall natural disaster risk for Merrimack County?
Merrimack County has a composite FEMA National Risk Index score of 78.2 out of 100, placing it in the Low category and the 78th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Merrimack County?
The three highest-rated hazards are Ice Storm (High, $1M EAL), Lightning (High, $1M EAL), Riverine Flood (Medium, $34M EAL). These account for most of the county's expected annual losses.
How does Merrimack County compare to other New Hampshire counties?
Merrimack County ranks #4 of 10 New Hampshire counties for overall natural disaster risk, with a low rating.
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. Merrimack County's $49M EAL is a statistical average, not a guarantee for any specific year or address.