Merrimack County Disaster Risk

Merrimack County has a FEMA National Risk Index rating of Relatively Low, placing it in the 78th percentile nationally out of 3,144 counties. This composite score reflects the county's overall exposure to natural hazards including floods, wildfires, tornadoes, earthquakes, and hurricanes, weighted by expected annual loss and social vulnerability.

Merrimack County is evaluated for five major natural hazard types: flooding (86th percentile), hurricane (85th percentile), earthquake (76th percentile), tornado (56th percentile), wildfire (35th percentile). The highest-risk hazard is flooding at the 86th percentile nationally. These scores are derived from FEMA's National Risk Index, which analyzes expected annual loss, social vulnerability, and community resilience for each hazard type.

Merrimack County's composite risk percentile is 78th, compared to the New Hampshire state average of 70th percentile. The state's overall risk rating is Relatively Low. This means Merrimack County faces higher natural disaster risk than the typical county in New Hampshire.

Yes, Merrimack County's flooding risk is at the 86th percentile nationally. This places it in the top quartile for this hazard type.

FEMA's National Risk Index (NRI) calculates risk scores for 18 natural hazard types across all U.S. counties and census tracts. The composite score combines Expected Annual Loss (estimated dollar losses from each hazard), Social Vulnerability (demographic factors affecting disaster impact), and Community Resilience (ability to recover). Percentile scores rank each county against all 3,144 U.S. counties, and risk ratings range from Very Low to Very High.

Merrimack County's composite risk score of 78th percentile is above the New Hampshire state average of 70th percentile. This elevated risk is driven by flooding exposure (86th percentile), along with hurricane and earthquake and tornado risk. Geographic location, terrain, climate patterns, and proximity to flood zones or fault lines all influence a county's risk profile.