Updated May 2026
Flood Risk in New Hampshire
New Hampshire carries a relatively low statewide average risk score of 15, with 100% of its 10 counties at A or B. 0 counties are in the F (extreme) tier, typically along major rivers or flood-prone basins. Statewide NFIP take-up is modest at 133 total claims.
Grade Distribution Across New Hampshire
The grade mix is dominated by A — 90% of counties — meaning the typical place in this state has very low historical flood loss. The handful of B/C/D/F counties below define where risk is concentrated.
How New Hampshire Compares Nationally
The U.S. county-level average composite score is 12. New Hampshire sits at 15, which is 3 points above the national average — meaningfully more flood-exposed than the typical U.S. state. 111 federal flood-related disaster declarations across 10 counties is one of the highest counts in the dataset — about 11.1 per county. Most counties have lived through multiple federally declared floods.
For full national context — every state ranked by average score and total claims — see the all-states overview. The riskiest-counties ranking and highest-payouts ranking drill into where loss is concentrated. Real-time stream-gauge readings are at USGS Water Data.
Riskiest in New Hampshire
| County | Grade | Score |
|---|---|---|
| Grafton | B | 23 |
| Hillsborough | A | 20 |
| Cheshire | A | 16 |
| Sullivan | A | 15 |
| Carroll | A | 14 |
Safest in New Hampshire
| County | Grade | Score |
|---|---|---|
| Rockingham | A | 11 |
| Merrimack | A | 12 |
| Strafford | A | 12 |
| Belknap | A | 13 |
| Coos | A | 13 |
How New Hampshire's Risk Is Calculated
Every county in New Hampshire is scored on the same four factors that drive every county nationwide: NFIP claims density (40%), federally declared flood-disaster frequency (25%), average claim severity (20%), and year-over-year trend (15%). Source data comes from the public FEMA flood-mapping program and OpenFEMA endpoints. Detailed weighting math, plus the data's known limitations (county-level granularity, NFIP-participation bias, historical bias), is on the methodology page.
All 10 Counties in New Hampshire
Sorted by flood risk score, highest to lowest.
| # | County | Grade | Score | Claims | Payouts | Disasters |
|---|---|---|---|---|---|---|
| 1 | Grafton | B | 23 | 13 | $56,526 | 14 |
| 2 | Hillsborough | A | 20 | 11 | $327,247 | 9 |
| 3 | Cheshire | A | 16 | 5 | $85,958 | 12 |
| 4 | Sullivan | A | 15 | 4 | $30,403 | 13 |
| 5 | Carroll | A | 14 | 9 | $157,053 | 12 |
| 6 | Belknap | A | 13 | 0 | $0 | 10 |
| 7 | Coos | A | 13 | 6 | $111,125 | 11 |
| 8 | Merrimack | A | 12 | 3 | $4,234 | 9 |
| 9 | Strafford | A | 12 | 2 | $57,798 | 8 |
| 10 | Rockingham | A | 11 | 80 | $1,846,561 | 13 |
Frequently Asked Questions
What is the average flood risk score in New Hampshire?
New Hampshire's average composite flood risk score is 15 on a 0–100 scale, computed as the mean of all 10 county scores. That is 3 points above the U.S. county-level average of 12. Score components: 40% claims density, 25% disaster frequency, 20% claim severity, 15% trend.
Which counties in New Hampshire have the highest flood risk?
The riskiest county in New Hampshire is Grafton with a composite score of 23 (grade B). The next four — Hillsborough, Cheshire, Sullivan, Carroll — round out the top-five most exposed places in the state.
How many NFIP flood-insurance claims has New Hampshire filed?
FEMA's National Flood Insurance Program shows 133 claims on file from New Hampshire, with combined payouts of $2,676,905 across the dataset. 9 of the state's 10 counties have at least one NFIP claim recorded.
Are FEMA flood maps the same as your risk score?
No. The flood risk score on this page is a county-wide composite drawn from claims, disasters, severity, and trend. FEMA Flood Insurance Rate Maps (FIRMs, available at fema.gov/flood-maps) are parcel-level zone designations based on hydrologic modeling. The two answer different questions; serious decisions about insurance or building should use both, plus real-time hydrology from USGS Water Data.
When was the New Hampshire data last updated?
These figures were refreshed from the OpenFEMA API on 2026-05-16. FEMA itself publishes new NFIP claims on a quarterly cycle, so the data may lag actual events by up to three months.
Flood risk profile for New Hampshire: 10 counties, 133 NFIP claims, average composite score 15.
this entity is one of the data points covered by this site’s U.S. flood risk, NFIP claims, and disaster declarations dataset. The detail above comes directly from FEMA OpenFEMA datasets including the National Flood Hazard Layer and NFIP claims; the context that follows situates the headline numbers against the broader distribution across U.S. ZIPs, counties, and states.
The methodology behind every numeric value on this page is publicly documented on the FEMA OpenFEMA datasets including the National Flood Hazard Layer and NFIP claims portal and described in detail on this site’s methodology page. Refresh cadence varies by underlying series; the page surfaces the as-of date for each number so readers can trace any figure back to the source release.
For readers using this page as a decision input, the related-entity pages elsewhere on the site provide the comparison set. The most useful comparison for this entity is typically a peer within U.S. ZIPs, counties, and states with similar size, similar exposure, or similar geography — not the national-level summary alone.