Photo: Pvmoutside · CC BY-SA 3.0FEMA expects less hazard damage per building in Groton than in 84% of U.S. towns, mostly from river and rain flooding
On FEMA’s National Risk Index, Groton gets an A− for hazard risk: lower expected damage per building than 84% of U.S. towns, #91 of 283 in Massachusetts. Most of that expected damage is river and rain flooding (76%), then hurricanes (10%). Flood insurance has paid 1 claim here since 2010.
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 Groton 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
Earthquakes
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 Groton’s grade
River and rain flooding is 76% of the building damage FEMA expects in Groton, and Groton’s rate of river and rain flooding damage is lower than 68% of U.S. census tracts. Ice storms add 3%, at a rate in the top 8% of U.S. census tracts.
A− #91 of 283 in Massachusetts; lower expected damage per building than 84% of U.S. towns (21,298).
Groton’s residents live in 2 census tracts; FEMA’s figures are combined by where they live.
The typical Massachusetts town has lower expected damage than 76% of U.S. towns; within the state, Groton has less expected damage per building than 68% of Massachusetts towns.
In dollars, FEMA expects about $2.9M a year in losses across Groton: $2.3M to buildings, the rest to people and crops.
Does Groton flood? Rarely: 1 flood claim since 2010
Every paid claim on a federal flood insurance policy in Groton, from FEMA’s records: 0.3 per 1,000 homes, fewer than 96% of the 13,809 U.S. towns with a flood insurance record.
- The March 2010 nor’easter1 claim · $12K
Groton isn’t in FEMA’s Community Rating System, which cuts flood insurance up to 45% in towns that do extra flood-proofing.
Insurance rates: Middlesex County.13 federal disasters brought FEMA money to Groton
Disasters that paid out in Groton itself (aid to households or repair grants to the Town of Groton), newest first, with that year’s flood claims.
- 2018Severe Winter Storm and Snowstorm$57K to the Town of Groton for repairs
- 2015Severe Winter Storm, Snowstorm, and Flooding$71K to the Town of Groton for repairs
- 2013Severe Winter Storm, Snowstorm, and Flooding$42K to the Town of Groton for repairs
- 2011Severe Storm and Snowstorm$243K to the Town of Groton for repairs
- 2011Hurricane Irene$20K to the Town of Groton for repairs
- 2011Severe Winter Storm and Snowstorm$39K to the Town of Groton for repairs
Show all 13
- 2010Severe Storms and Flooding38 households applied for aid$46K aid approved$97K to the Town of Groton for repairs1 flood claim paid that year
- 2008Severe Winter Storm and Flooding$270K to the Town of Groton for repairs
- 2006Severe Storms and Flooding2 households applied for aid$568 aid approved$4K to the Town of Groton for repairs
- 2005Record And/or Near Record Snow$59K to the Town of Groton for repairs
- 2003Snow$36K to the Town of Groton for repairs
- 2003Snow$26K to the Town of Groton for repairs
- 2001Snow$25K to the Town of Groton for repairs
Middlesex County has had 27 natural disasters declared by the President since 1953, most often winter storms, then hurricanes and tropical storms. Not counted: the 2005 Hurricane Katrina evacuee emergency, which covered counties that took in evacuees.
Old photos of Groton after a storm or flood belong in the town’s history. Add one, or share what you remember below.
Add to the Groton archive →Groton and its neighbors
Groton is 6th of the 8 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 |
|---|---|---|---|
| Ayer | A+less damage than 95% | river and rain flooding | 3 |
| Littleton | Aless damage than 93% | river and rain flooding | 12 |
| Shirley | Aless damage than 88% | river and rain flooding | 9 |
| Westford | Aless damage than 86% | river and rain flooding | 8 |
| Dunstable | A−less damage than 84% | river and rain flooding | — |
| Groton | A−less damage than 84% | river and rain flooding | 1 |
| Pepperell | A−less damage than 78% | river and rain flooding | 15 |
| Tyngsborough | Bless damage than 62% | river and rain flooding | 25 |
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 Groton 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.
- Drop, cover and hold on.
- Strap tall furniture and the water heater to the wall.
- Know how to shut off the gas.
- 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 Groton
Is Groton at risk for natural disasters?
On FEMA’s National Risk Index, Groton has lower expected damage per building than 84% of U.S. towns: A− for hazard risk, #91 of 283 in Massachusetts. Most of the expected damage is river and rain flooding (76%) and hurricanes (10%). This is FEMA’s model of an average year for today’s buildings, not a forecast.
Does Groton flood?
Flood insurance has paid 1 claim in Groton since 2010, $12K in all, or 0.3 per 1,000 homes, fewer than 96% of U.S. towns with a flood insurance record. The most claims came from March 2010 Nor'easter (1).
Is Groton 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 Middlesex County, 54% of homes in mapped flood zones carry federal flood insurance, and 1.0% of all homes do.
How much is flood insurance in Groton?
FEMA’s Community Rating System list shows no discount for Groton’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 Groton?
By FEMA money that reached Groton, Severe Winter Storm and Flooding (2008): $270K to the Town of Groton for repairs. By flood claims, March 2010 Nor'easter: 1 paid, $12K.
Is Groton at risk from river and rain flooding?
It is the largest share of the building damage FEMA expects here (76%), and Groton’s rate for it is lower than 68% of U.S. census tracts.
Storm stories
Memories, warnings and help from neighbors in Groton.
Sources: FEMA National Risk Index v1.20 (December 2025), census-tract table, combined by where Groton’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.