Photo: Quintin Soloviev · CC BY 4.0FEMA expects less hazard damage per building in Portsmouth than in 74% of U.S. towns, mostly from river and rain flooding
On FEMA’s National Risk Index, Portsmouth gets a B+ for hazard risk: lower expected damage per building than 74% of U.S. towns, #15 of 126 in New Hampshire. Most of that expected damage is river and rain flooding (63%), then earthquakes (13%). Flood insurance has paid 34 claims here since 1979.
Graded on FEMA’s expected yearly building damage per dollar of building value (NRI v1.20, December 2025), weighted by where residents live; flood claims are shown, not graded. How hazard risk is graded
What stands out about Portsmouth’s natural hazards
From FEMA’s model and FEMA’s records, below.
What Portsmouth faces
Each hazard’s share of the building damage FEMA expects here, and how its rate compares with the rest of the country.
River and rain flooding
Earthquakes
Coastal flooding
Hurricanes
Shares are of FEMA’s expected building damage, the measure the grade uses; ranks compare each hazard’s building-damage rate with all 85,154 U.S. census tracts. In FEMA’s terms, river and rain flooding is FEMA’s “Inland Flooding” (rivers and streams overflowing their banks, or rain overwhelming drainage). FEMA defines coastal flooding as high or rising tides and storm surge, so surge damage is counted there. Drought isn’t listed: FEMA counts its losses in crops only.
What’s behind Portsmouth’s grade
River and rain flooding is 63% of the building damage FEMA expects in Portsmouth, and Portsmouth’s rate of river and rain flooding damage is lower than 71% of U.S. census tracts. Coastal flooding adds 12%, at a rate in the top 2% of U.S. census tracts.
B+ #15 of 126 in New Hampshire; lower expected damage per building than 74% of U.S. towns (21,298).
Portsmouth’s residents live in 7 census tracts; FEMA’s figures are combined by where they live.
The typical New Hampshire town has higher expected damage than 58% of U.S. towns; within the state, Portsmouth has less expected damage per building than 89% of New Hampshire towns.
In dollars, FEMA expects about $5.8M a year in losses across Portsmouth: $5.1M to buildings, the rest to people and crops.
Does Portsmouth flood? Sometimes: 34 flood claims since 1979
Every paid claim on a federal flood insurance policy in Portsmouth, from FEMA’s records: 3.0 per 1,000 homes, fewer than 52% of the 13,809 U.S. towns with a flood insurance record.
- The March 2010 nor’easter6 claims · $42K
- The “Halloween” storm1 claim · $3K
Portsmouth isn’t in FEMA’s Community Rating System, which cuts flood insurance up to 45% in towns that do extra flood-proofing.
Insurance rates: Rockingham County.5 federal disasters brought FEMA money to Portsmouth
Disasters that paid out in Portsmouth itself (aid to households or repair grants to the City of Portsmouth), newest first, with that year’s flood claims.
- 2024Severe Storms and Flooding$7K to the City of Portsmouth for repairs6 flood claims paid that year
- 2013Severe Winter Storm and Snowstorm$106K to the City of Portsmouth for repairs
- 2011Hurricane Irene$12K to the City of Portsmouth for repairs
- 2007Severe Storms and Flooding9 households applied for aid$2K aid approved3 flood claims paid that year
- 2006Severe Storms and Flooding154 households applied for aid$224K aid approved2 flood claims paid that year
Rockingham County has had 29 natural disasters declared by the President since 1953, most often severe storms, then winter storms. Not counted: the 2005 Hurricane Katrina evacuee emergency, which covered counties that took in evacuees.
Old photos of Portsmouth after a storm or flood belong in the town’s history. Add one, or share what you remember below.
Add to the Portsmouth archive →Portsmouth and its neighbors
Portsmouth is 2nd of the 5 graded towns here, from least expected damage per building to most. Tap a town to see its hazards.
| Town | Hazard risk | Mostly (buildings) | Flood claims |
|---|---|---|---|
| Greenland | Aless damage than 87% | river and rain flooding | 12 |
| Portsmouth | B+less damage than 74% | river and rain flooding | 34 |
| Eliot | B+less damage than 69% | river and rain flooding | 8 |
| Kittery | Bless damage than 64% | river and rain flooding | 18 |
| Rye | Cmore damage than 71% | river and rain flooding | 215 |
| New Castle | — | 827 residents; we grade 1,000+ | |
| Newington | — | 939 residents; we grade 1,000+ | |
| South Eliot | — | a Census area inside a town; graded with the town | |
Hazard risk = FEMA’s expected yearly building damage per dollar of building value, vs. the 21,298 U.S. towns we grade; the map is shaded by fifths of the same scale. Flood claims = paid federal flood insurance claims on record.
Get ready for what Portsmouth faces
A short kit for the hazards that drive the building damage here, what to check before you buy, and where neighbors get alerts.
- Turn around at flooded roads: a foot of moving water can carry off a car.
- Flood insurance usually takes 30 days to start, so buy it before the forecast.
- Keep papers and medicines up high, in a grab-and-go bag.
- Drop, cover and hold on.
- Strap tall furniture and the water heater to the wall.
- Know how to shut off the gas.
- Know your evacuation zone and the way off the coast.
- Storm surge comes fast: leave when you’re told, not when the water arrives.
- Move cars to high ground before king tides and nor’easters.
- The season runs June through November and peaks from mid-August to mid-October.
- Bring in porch furniture and anything the wind can throw.
- Fill the gas tank and charge phones before the storm arrives.
- Look up the address on FEMA’s flood map.
- Ask the seller or landlord whether it has ever flooded, and what flood insurance costs there.
- Get a flood insurance quote early: policies usually start 30 days after you buy.
Know where neighbors sign up for alerts? Add it to the Handbook so everyone has it.
Questions about natural hazards in Portsmouth
Is Portsmouth at risk for natural disasters?
On FEMA’s National Risk Index, Portsmouth has lower expected damage per building than 74% of U.S. towns: B+ for hazard risk, #15 of 126 in New Hampshire. Most of the expected damage is river and rain flooding (63%) and earthquakes (13%). This is FEMA’s model of an average year for today’s buildings, not a forecast.
Does Portsmouth flood?
Flood insurance has paid 34 claims in Portsmouth since 1979, $518K in all, or 3.0 per 1,000 homes, fewer than 52% of U.S. towns with a flood insurance record. 2 properties have flooded more than once. The most claims came from March 2010 Nor'easter (6).
Is Portsmouth in a flood zone?
Flood zones are drawn street by street, so the answer depends on the address: look it up on FEMA’s flood map. In Rockingham County, 37% of homes in mapped flood zones carry federal flood insurance, and 2.2% of all homes do.
How much is flood insurance in Portsmouth?
FEMA’s Community Rating System list shows no discount for Portsmouth’s flood program. Premiums depend on the building; policies usually start 30 days after you buy, so get a quote early.
What was the biggest storm in Portsmouth?
By FEMA money that reached Portsmouth, Severe Storms and Flooding (2006): 154 households applied for aid, $224K approved. By flood claims, March 2010 Nor'easter: 6 paid, $42K.
Is Portsmouth at risk from river and rain flooding?
It is the largest share of the building damage FEMA expects here (63%), and Portsmouth’s rate for it is lower than 71% of U.S. census tracts.
Storm stories
Memories, warnings and help from neighbors in Portsmouth.
Sources: FEMA National Risk Index v1.20 (December 2025), census-tract table, combined by where Portsmouth’s residents lived in the 2020 census; OpenFEMA: NFIP redacted claims, multiple-loss properties, community status book and residential penetration rates, housing assistance (owners and renters), public assistance funded projects, hazard mitigation properties and disaster declarations. Homes: Census ACS 2020–24. Preparedness tips: Ready.gov. FEMA’s model is an average of expected damage, not a forecast. How hazard risk is graded.