Grafton County, New Hampshire Natural Disaster Risk
FEMA National Risk Index assessment · NH
MediumComposite Risk Score
National percentile: 82th
Grafton County faces medium composite natural disaster risk (NRI Risk Index score 81.8, 82th national percentile), driven primarily by landslide and winter weather exposure. Expected annual loss across all 18 hazard types is $50M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
Grafton County carries a medium composite natural disaster risk, with a National Risk Index score of 81.8 out of 100 — placing it in the 82nd national percentile and near the national midpoint for natural-disaster risk. The score blends Expected Annual Loss, Social Vulnerability, and Community Resilience across all 18 FEMA hazard types.
Risk here concentrates in landslide (downhill movement of rock, soil, and debris on unstable slopes) at Medium risk — $544K in expected annual loss and about 3.35 events per year; winter weather (heavy snow, blizzards, and hazardous winter conditions) at High risk — $608K in expected annual loss and about 22.07 events per year; and riverine flood (rivers and streams overflowing their banks after heavy rain or snowmelt) at Medium risk — $43M in expected annual loss and about 4.29 events per year. Across all hazards, FEMA estimates $50M in expected annual loss for a population of 91K.
Beyond physical exposure, Grafton County has a low social vulnerability rating (how susceptible the population is to harm) and a high community resilience rating (its capacity to prepare for and recover from disasters). A less vulnerable population paired with strong resilience helps the community absorb and recover from events.
History supports the rating: Grafton County has received 40 federal disaster declarations since 1973, including 17 for severe storm events and 8 for flood events. The most recent was Severe Storm and Flooding (severe storm), declared in August 2024.
Among 10 New Hampshire counties, Grafton County ranks #3 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Landslide | Medium | 3.35 / yr | $544K |
| Winter Weather | High | 22.07 / yr | $608K |
| Riverine Flood | Medium | 4.29 / yr | $43M |
| Lightning | Medium | 19.69 / yr | $828K |
| Hurricane | Low | 0.06 / yr | $2M |
| Ice Storm | Medium | 0.60 / yr | $332K |
| Avalanche | Low | 0.01 / yr | $13K |
| Earthquake | Low | 0.00 / yr | $848K |
| Cold Wave | Low | 3.92 / yr | $1M |
| Strong Wind | Low | 0.79 / yr | $577K |
| Heat Wave | Low | 1.01 / yr | $310K |
| Wildfire | Very Low | 0.00 / yr | $16K |
| Tornado | Very Low | 0.18 / yr | $378K |
| Hail | Very Low | 1.62 / yr | $75K |
| 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
Grafton County has received 40 federal disaster declarations since 1973, most recently Severe Storm and Flooding in August 2024. Most frequent causes: Severe Storm (17), Flood (8), Hurricane (6).
| Declared | Type | Disaster |
|---|---|---|
| August 2024 | Severe Storm | Severe Storm and Flooding |
| July 2024 | Winter Storm | Severe Winter Storm and Flooding |
| April 2024 | Severe Storm | Severe Storms 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 |
| August 2019 | Severe Storm | Severe Storm and Flooding |
| January 2018 | Severe Storm | Severe Storm and Flooding |
Showing the 10 most recent of 40 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Grafton County?
Grafton County has a composite FEMA National Risk Index score of 81.8 out of 100, placing it in the Medium category and the 82th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Grafton County?
The three highest-rated hazards are Landslide (Medium, $544K EAL), Winter Weather (High, $608K EAL), Riverine Flood (Medium, $43M EAL). These account for most of the county's expected annual losses.
How does Grafton County compare to other New Hampshire counties?
Grafton County ranks #3 of 10 New Hampshire counties for overall natural disaster risk, with a medium rating.
How many federally declared disasters has Grafton County had?
FEMA records 40 federal disaster declarations for Grafton County since 1973, most often 17 for severe storm events and 8 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. Grafton County's $50M EAL is a statistical average, not a guarantee for any specific year or address.