Signer's House and Matthew Thornton Cemetery · Photo: Jane023 · CC BY-SA 4.0FEMA expects more hazard damage per building in Merrimack than in 65% of U.S. towns, mostly from river and rain flooding
On FEMA’s National Risk Index, Merrimack gets a C+ for hazard risk: higher expected damage per building than 65% of U.S. towns, #75 of 126 in New Hampshire. Most of that expected damage is river and rain flooding (76%), then hurricanes (15%). Flood insurance has paid 51 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 Merrimack’s natural hazards
From FEMA’s model and FEMA’s records, below.
What Merrimack 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
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 Merrimack’s grade
River and rain flooding is 76% of the building damage FEMA expects in Merrimack, and Merrimack’s rate of river and rain flooding damage is higher than 74% of U.S. census tracts. Ice storms add 2%, at a rate in the top 8% of U.S. census tracts.
C+ #75 of 126 in New Hampshire; higher expected damage per building than 65% of U.S. towns (21,298).
Merrimack’s residents live in 6 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, Merrimack has more expected damage per building than 59% of New Hampshire towns.
In dollars, FEMA expects about $8.9M a year in losses across Merrimack: $8.0M to buildings, the rest to people and crops.
Does Merrimack flood? Sometimes: 51 flood claims since 1979
Every paid claim on a federal flood insurance policy in Merrimack, from FEMA’s records: 4.6 per 1,000 homes, more than 58% of the 13,809 U.S. towns with a flood insurance record.
- The March 2010 nor’easter5 claims · $26K
Merrimack isn’t in FEMA’s Community Rating System, which cuts flood insurance up to 45% in towns that do extra flood-proofing.
Insurance rates: Hillsborough County.13 federal disasters brought FEMA money to Merrimack
Disasters that paid out in Merrimack itself (aid to households or repair grants to the Town of Merrimack), newest first, with that year’s flood claims.
- 2015Severe Winter Storm and Snowstorm$34K to the Town of Merrimack for repairs
- 2013Severe Winter Storm and Snowstorm$58K to the Town of Merrimack for repairs
- 2012Hurricane Sandy$20K to the Town of Merrimack for repairs
- 2011Severe Storm and Snowstorm$160K to the Town of Merrimack for repairs
- 2011Hurricane Irene$16K to the Town of Merrimack for repairs
- 2010Severe Storms and Flooding$117K to the Town of Merrimack for repairs
Show all 13
- 2010Severe Winter Storm$127K to the Town of Merrimack for repairs
- 2008Severe Winter Storm$120K to the Town of Merrimack for repairs1 flood claim paid that year
- 2007Severe Storms and Flooding49 households applied for aid$89K aid approved$128K to the Town of Merrimack for repairs16 flood claims paid that year
- 2006Severe Storms and Flooding177 households applied for aid$334K aid approved$673K to the Town of Merrimack for repairs14 flood claims paid that year
- 2005Severe Storms and Flooding4 households applied for aid$1K aid approved$4K to the Town of Merrimack for repairs
- 2005Record Snow$39K to the Town of Merrimack for repairs
- 2005Record And/or Near Record Snow$38K to the Town of Merrimack for repairs
Hillsborough County has had 26 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 Merrimack after a storm or flood belong in the town’s history. Add one, or share what you remember below.
Add to the Merrimack archive →Merrimack and its neighbors
Merrimack is 7th of the 7 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 |
|---|---|---|---|
| Bedford | Bless damage than 64% | river and rain flooding | 17 |
| Hollis | Bless damage than 55% | river and rain flooding | 3 |
| Amherst | B−more damage than 52% | river and rain flooding | 43 |
| Nashua | B−more damage than 54% | river and rain flooding | 40 |
| Litchfield | B−more damage than 54% | river and rain flooding | 2 |
| Manchester | C+more damage than 58% | river and rain flooding | 41 |
| Merrimack | C+more damage than 65% | river and rain flooding | 51 |
| East Merrimack | — | 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 Merrimack 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.
- 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 Merrimack
Is Merrimack at risk for natural disasters?
On FEMA’s National Risk Index, Merrimack has higher expected damage per building than 65% of U.S. towns: C+ for hazard risk, #75 of 126 in New Hampshire. Most of the expected damage is river and rain flooding (76%) and hurricanes (15%). This is FEMA’s model of an average year for today’s buildings, not a forecast.
Does Merrimack flood?
Flood insurance has paid 51 claims in Merrimack since 1979, $1.4M in all, or 4.6 per 1,000 homes, more than 58% of U.S. towns with a flood insurance record. 9 properties have flooded more than once. The most claims came from March 2010 Nor'easter (5).
Is Merrimack 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 Hillsborough County, 34% of homes in mapped flood zones carry federal flood insurance, and 0.7% of all homes do.
How much is flood insurance in Merrimack?
FEMA’s Community Rating System list shows no discount for Merrimack’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 Merrimack?
By FEMA money that reached Merrimack, Severe Storms and Flooding (2006): 177 households applied for aid, $334K approved, and $673K to the Town of Merrimack for repairs. By flood claims, March 2010 Nor'easter: 5 paid, $26K.
Is Merrimack at risk from river and rain flooding?
It is the largest share of the building damage FEMA expects here (76%), and Merrimack’s rate for it is higher than 74% of U.S. census tracts.
Storm stories
Memories, warnings and help from neighbors in Merrimack.
Sources: FEMA National Risk Index v1.20 (December 2025), census-tract table, combined by where Merrimack’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.