riskbycounty
FEMA NRI 1.19.0Updated Nov 2023 · Coverage 2014–2023Methodology

Merrimack County Disaster Risk

Merrimack County, New Hampshire

FEMA Risk Rating

Relatively Low

National Percentile

78th

of 3,144 counties

State Rank

#4

of 10 (1 = highest risk)

Flood Risk

86th

percentile

Hazard Risk Breakdown

Flood

River, coastal, and surface flooding risk

Moderate

Higher than 86% of US counties

Wildfire

Wildland and wildland-urban interface fire risk

Very Low

Higher than 35% of US counties

Tornado

Tornado and severe thunderstorm risk

Relatively Low

Higher than 56% of US counties

Earthquake

Seismic activity and ground shaking risk

Relatively Low

Higher than 76% of US counties

Hurricane

Tropical cyclone and hurricane risk

Moderate

Higher than 85% of US counties

Risk Overview

About Natural Disaster Risk in Merrimack County, New Hampshire

Merrimack County Above National Average

Merrimack County's composite risk score of 78.21 exceeds the national average of 69.89 by about 8 points, placing it in the "Relatively Low" category. Residents face above-average disaster exposure compared to most U.S. counties.

Second-Highest Risk in New Hampshire

Merrimack County ranks second-riskiest among New Hampshire's eight counties with a composite score of 78.21, trailing only Hillsborough (89.76). It exceeds the state average of 69.89 across all major hazard categories.

Riskier Than Belknap and Cheshire

Merrimack County (78.21) significantly exceeds neighboring Belknap (57.38) and Cheshire (60.50) counties to the south. Its tornado risk of 56.17 and flood risk of 85.81 reflect its central location in New Hampshire's hazard corridor.

Floods, Tornadoes, and Earthquakes Loom

Merrimack County's top hazards are flood (85.81), hurricane (84.81), and tornado (56.17), all significantly elevated compared to state averages. Earthquake risk of 76.14 adds further concern, reflecting the county's convergence of multiple disaster zones.

Secure Multi-Hazard Insurance Coverage

Merrimack County residents should carry separate flood insurance and comprehensive windstorm/tornado coverage given the combined threats of 85.81 flood, 84.81 hurricane, and 56.17 tornado risks. Standard policies rarely provide adequate protection against all three.

Source: FEMA National Risk Index · Narrative reviewed by Evan Brooks, Data Editor

Preparedness Guide

What to Prepare for in Merrimack County

Top Hazards by Exposure

  1. #1
    FloodPrepare
    86th percentile
  2. #2
    HurricanePrepare
    85th percentile
  3. #3
    EarthquakePrepare
    76th percentile

Source: FEMA National Risk Index v1.19.0 · Percentiles are national (3,144 counties)

Risk Advisory: Merrimack County

Risk Verdict

With a national percentile rank of 78th, Merrimack County faces below-average hazard exposure relative to U.S. counties as a whole. Proactive preparedness — not reactive response — is key to managing life in one of the country's higher-risk counties; Merrimack County residents should plan accordingly.

Hazard Breakdown

Flood risk is Merrimack County's dominant natural hazard, ranked at the 86th percentile nationally under FEMA's National Risk Index. Hurricane ranks second at the 85th percentile nationally. Additional tracked hazards include earthquake (76th percentile), tornado (56th percentile), wildfire (35th percentile).

Preparedness Context

With flood risk ranking at the 86th percentile nationally, Merrimack County residents face one of the most financially damaging hazards without specialized coverage. Flood insurance through the NFIP or a private carrier is worth evaluating regardless of current mortgage requirements. The county's second-ranked hazard, hurricane at the 85th percentile nationally, means Merrimack County residents face compounding risks from multiple natural hazard types during peak seasons. Registering for Merrimack County's county emergency alert system — typically through the county emergency management office's website — ensures households receive early warning when flood events develop faster than forecast.

Regional Context

At 8.3 points above the New Hampshire state average, Merrimack County carries meaningfully higher natural disaster exposure than a typical New Hampshire county.

Is your household prepared for Merrimack County's hazards?

Review FEMA's county-specific preparedness checklists and emergency planning guides.

FEMA Ready Guide →

Frequently Asked Questions

What is the natural disaster risk in Merrimack County, NH?
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.
What types of natural hazards affect Merrimack County?
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.
How does Merrimack County risk compare to the New Hampshire average?
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.
Is Merrimack County at risk for flooding?
Yes, Merrimack County's flooding risk is at the 86th percentile nationally. This places it in the top quartile for this hazard type.
How is natural disaster risk measured?
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.
Why is Merrimack County higher risk than average?
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.
By Evan Brooks, Data EditorUpdated Reviewed by Evan Brooks, Data Editor

Data Source

Risk data sourced from the FEMA National Risk Index (NRI). Risk scores are relative rankings (0–100) across all US counties — not absolute risk measures. Higher scores indicate higher relative risk compared to other counties.

Disclaimer: This data is informational only. It is not financial, insurance, or legal advice. Always consult a qualified professional before making insurance or real estate decisions.