Coos County, New Hampshire Natural Disaster Risk
FEMA National Risk Index assessment · NH
LowComposite Risk Score
National percentile: 73th
Coos County faces low composite natural disaster risk (NRI Risk Index score 72.8, 73th national percentile), driven primarily by avalanche and winter weather exposure. Expected annual loss across all 18 hazard types is $27M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
FEMA's National Risk Index rates Coos County at low composite risk, with a National Risk Index score of 72.8 out of 100 — placing it in the 73rd national percentile and below the national average for natural-disaster risk. The score blends Expected Annual Loss, Social Vulnerability, and Community Resilience across all 18 FEMA hazard types.
Most of Coos County's expected losses come from avalanche (fast-moving snow and debris sliding down steep mountain slopes) at Very High risk — $5M in expected annual loss and about 0.27 events per year; winter weather (heavy snow, blizzards, and hazardous winter conditions) at High risk — $312K in expected annual loss and about 24.09 events per year; and cold wave (prolonged spells of dangerously low temperatures) at Medium risk — $5M in expected annual loss and about 6.81 events per year. Across all hazards, FEMA estimates $27M in expected annual loss for a population of 31K.
Beyond physical exposure, Coos County has a medium social vulnerability rating (how susceptible the population is to harm) and a medium community resilience rating (its capacity to prepare for and recover from disasters). Both measures sit toward the lower end, indicating relatively modest population sensitivity.
The federal record bears this out: Coos County has received 28 federal disaster declarations since 1973, including 10 for severe storm events and 6 for flood events. The most recent was Severe Storm and Flooding (severe storm), declared in August 2024.
Among 10 New Hampshire counties, Coos County ranks #5 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Avalanche | Very High | 0.27 / yr | $5M |
| Winter Weather | High | 24.09 / yr | $312K |
| Cold Wave | Medium | 6.81 / yr | $5M |
| Landslide | Low | 2.54 / yr | $16K |
| Riverine Flood | Medium | 2.39 / yr | $15M |
| Hurricane | Low | 0.05 / yr | $1M |
| Ice Storm | Medium | 0.25 / yr | $180K |
| Lightning | Low | 18.71 / yr | $219K |
| Earthquake | Very Low | 0.00 / yr | $222K |
| Strong Wind | Low | 0.39 / yr | $182K |
| Wildfire | Very Low | 0.00 / yr | $5K |
| Heat Wave | Very Low | 0.31 / yr | $24K |
| Tornado | Very Low | 0.12 / yr | $63K |
| Hail | Very Low | 0.90 / yr | $15K |
| Coastal Flood | Very Low | 0.00 / yr | $0 |
| Drought | Very Low | 0.00 / yr | $0 |
| Tsunami | Very Low | 0.00 / yr | $0 |
| Volcanic Activity | Very Low | 0.00 / yr | $0 |
Disaster History
Coos County has received 28 federal disaster declarations since 1973, most recently Severe Storm and Flooding in August 2024. Most frequent causes: Severe Storm (10), Flood (6), Hurricane (5).
| Declared | Type | Disaster |
|---|---|---|
| August 2024 | Severe Storm | Severe Storm and Flooding |
| February 2024 | Severe Storm | Severe Storm and Flooding |
| September 2023 | Flood | Severe Storms and Flooding |
| March 2023 | Severe Storm | Severe Storm and Flooding |
| April 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| January 2018 | Severe Storm | Severe Storm and Flooding |
| August 2017 | Severe Storm | Severe Storms and Flooding |
| November 2012 | Hurricane | Hurricane Sandy |
| October 2012 | Hurricane | Hurricane Sandy |
Showing the 10 most recent of 28 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Coos County?
Coos County has a composite FEMA National Risk Index score of 72.8 out of 100, placing it in the Low category and the 73th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Coos County?
The three highest-rated hazards are Avalanche (Very High, $5M EAL), Winter Weather (High, $312K EAL), Cold Wave (Medium, $5M EAL). These account for most of the county's expected annual losses.
How does Coos County compare to other New Hampshire counties?
Coos County ranks #5 of 10 New Hampshire counties for overall natural disaster risk, with a low rating.
How many federally declared disasters has Coos County had?
FEMA records 28 federal disaster declarations for Coos County since 1973, most often 10 for severe storm events and 6 for flood events. The most recent was Severe Storm and Flooding, declared in August 2024.
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. Coos County's $27M EAL is a statistical average, not a guarantee for any specific year or address.