Jonathan and Simon Hosmer House · Photo: John Phelan · CC BY-SA 4.0FEMA expects less hazard damage per building in Acton than in 84% of U.S. towns, mostly from river and rain flooding
On FEMA’s National Risk Index, Acton 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 (75%), then hurricanes (10%). Flood insurance has paid 35 claims here since 1978.
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 Acton’s natural hazards
From FEMA’s model and FEMA’s records, below.
What Acton 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 Acton’s grade
River and rain flooding is 75% of the building damage FEMA expects in Acton, and Acton’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).
Acton’s residents live in 6 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, Acton has less expected damage per building than 68% of Massachusetts towns.
In dollars, FEMA expects about $5.0M a year in losses across Acton: $4.5M to buildings, the rest to people and crops.
Does Acton flood? Sometimes: 35 flood claims since 1978
Every paid claim on a federal flood insurance policy in Acton, from FEMA’s records: 3.7 per 1,000 homes, more than 53% of the 13,809 U.S. towns with a flood insurance record.
- The March 2010 nor’easter10 claims · $157K
- Hurricane Bob1 claim · $346
Acton 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 Acton
Disasters that paid out in Acton itself (aid to households or repair grants to the Town of Acton), newest first, with that year’s flood claims.
- 2018Severe Winter Storm and Snowstorm$86K to the Town of Acton for repairs
- 2015Severe Winter Storm, Snowstorm, and Flooding$99K to the Town of Acton for repairs
- 2011Severe Storm and Snowstorm$34K to the Town of Acton for repairs
- 2011Hurricane Irene$7K to the Town of Acton for repairs
- 2011Severe Winter Storm and Snowstorm$60K to the Town of Acton for repairs
- 2010Severe Storms and Flooding97 households applied for aid$153K aid approved$17K to the Town of Acton for repairs11 flood claims paid that year
Show all 13
- 2008Severe Winter Storm and Flooding$39K to the Town of Acton for repairs
- 2006Severe Storms and Flooding3 households applied for aid$10K aid approved1 flood claim paid that year
- 2005Record And/or Near Record Snow$58K to the Town of Acton for repairs
- 2004Flooding5 households applied for aid$2K aid approved
- 2003Snow$68K to the Town of Acton for repairs
- 2003Snow$44K to the Town of Acton for repairs
- 2001Snow$47K to the Town of Acton for repairs3 flood claims paid that year
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 Acton after a storm or flood belong in the town’s history. Add one, or share what you remember below.
Add to the Acton archive →Acton and its neighbors
Acton is 6th 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 |
|---|---|---|---|
| Carlisle | Aless damage than 94% | river and rain flooding | 1 |
| Boxborough | Aless damage than 94% | river and rain flooding | — |
| Littleton | Aless damage than 93% | river and rain flooding | 12 |
| Concord | Aless damage than 86% | river and rain flooding | 45 |
| Westford | Aless damage than 86% | river and rain flooding | 8 |
| Acton | A−less damage than 84% | river and rain flooding | 35 |
| Stow | A−less damage than 83% | river and rain flooding | — |
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 Acton 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 Acton
Is Acton at risk for natural disasters?
On FEMA’s National Risk Index, Acton 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 (75%) and hurricanes (10%). This is FEMA’s model of an average year for today’s buildings, not a forecast.
Does Acton flood?
Flood insurance has paid 35 claims in Acton since 1978, $248K in all, or 3.7 per 1,000 homes, more than 53% of U.S. towns with a flood insurance record. 5 properties have flooded more than once. The most claims came from March 2010 Nor'easter (10).
Is Acton 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 Acton?
FEMA’s Community Rating System list shows no discount for Acton’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 Acton?
By FEMA money that reached Acton, Severe Storms and Flooding (2010): 97 households applied for aid, $153K approved, and $17K to the Town of Acton for repairs. By flood claims, March 2010 Nor'easter: 10 paid, $157K.
Is Acton at risk from river and rain flooding?
It is the largest share of the building damage FEMA expects here (75%), and Acton’s rate for it is lower than 68% of U.S. census tracts.
Storm stories
Memories, warnings and help from neighbors in Acton.
Sources: FEMA National Risk Index v1.20 (December 2025), census-tract table, combined by where Acton’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.