Photo: dwhartwig · CC BY 2.0FEMA puts Mason City’s expected hazard damage per building above that of 74% of U.S. towns, mostly from river and rain flooding
On FEMA’s National Risk Index, Mason City gets a C for hazard risk: higher expected damage per building than 74% of U.S. towns, #120 of 140 in Iowa. Most of that expected damage is river and rain flooding (77%), then tornadoes (19%). Flood insurance has paid 147 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 Mason City’s natural hazards
From FEMA’s model and FEMA’s records, below.
What Mason City 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
Tornadoes
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 Mason City’s grade
River and rain flooding is 77% of the building damage FEMA expects in Mason City, and Mason City’s rate of river and rain flooding damage is higher than 80% of U.S. census tracts. Tornadoes add 19%, at a rate in the top 1% of U.S. census tracts.
C #120 of 140 in Iowa; higher expected damage per building than 74% of U.S. towns (21,298).
Mason City’s residents live in 7 census tracts; FEMA’s figures are combined by where they live.
The typical Iowa town has lower expected damage than 57% of U.S. towns; within the state, Mason City has more expected damage per building than 86% of Iowa towns.
In dollars, FEMA expects about $14.3M a year in losses across Mason City: $9.9M to buildings, the rest to people and crops.
Does Mason City flood? Yes: 147 flood claims since 1978
Every paid claim on a federal flood insurance policy in Mason City, from FEMA’s records: 10.3 per 1,000 homes, more than 74% of the 13,809 U.S. towns with a flood insurance record.
- The Storm80 claims · $2.8M
Mason City isn’t in FEMA’s Community Rating System, which cuts flood insurance up to 45% in towns that do extra flood-proofing.
Insurance rates: Cerro Gordo County.5 federal disasters brought FEMA money to Mason City
Disasters that paid out in Mason City itself (aid to households or repair grants to the City of Mason City), newest first, with that year’s flood claims.
- 2018Severe Storms, Tornadoes, Straight-line Winds, and Flooding$145K to the City of Mason City for repairs7 flood claims paid that year
- 2016Severe Storms and Flooding$175K to the City of Mason City for repairs
- 2008Severe Storms, Tornadoes, and Flooding1,446 households applied for aid$2.6M aid approved$2.2M to the City of Mason City for repairs80 flood claims paid that year
- 2004Severe Storms, Tornadoes, and Flooding425 households applied for aid$465K aid approved$119K to the City of Mason City for repairs17 flood claims paid that year
- 1999Severe Storms and Flooding$238K to the City of Mason City for repairs11 flood claims paid that year
Cerro Gordo County has had 12 natural disasters declared by the President since 1953, most often floods, then severe storms. Not counted: the 2005 Hurricane Katrina evacuee emergency, which covered counties that took in evacuees.
Old photos of Mason City after a storm or flood belong in the town’s history. Add one, or share what you remember below.
Add to the Mason City archive →Get ready for what Mason City 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.
- Pick your spot now: the lowest floor, an inside room, no windows.
- A watch means be ready; a warning means take cover now.
- Keep shoes and a flashlight by the bed.
- 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 Mason City
Is Mason City at risk for natural disasters?
On FEMA’s National Risk Index, Mason City has higher expected damage per building than 74% of U.S. towns: C for hazard risk, #120 of 140 in Iowa. Most of the expected damage is river and rain flooding (77%) and tornadoes (19%). This is FEMA’s model of an average year for today’s buildings, not a forecast.
Does Mason City flood?
Flood insurance has paid 147 claims in Mason City since 1978, $3.3M in all, or 10.3 per 1,000 homes, more than 74% of U.S. towns with a flood insurance record. 7 properties have flooded more than once. The most claims came from Storm (80).
Is Mason City 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 Cerro Gordo County, 12% of homes in mapped flood zones carry federal flood insurance, and 0.4% of all homes do.
How much is flood insurance in Mason City?
FEMA’s Community Rating System list shows no discount for Mason City’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 Mason City?
By FEMA money that reached Mason City, Severe Storms, Tornadoes, and Flooding (2008): 1,446 households applied for aid, $2.6M approved, and $2.2M to the City of Mason City for repairs. By flood claims, Storm: 80 paid, $2.8M.
Is Mason City at risk from river and rain flooding?
It is the largest share of the building damage FEMA expects here (77%), and Mason City’s rate for it is higher than 80% of U.S. census tracts.
Storm stories
Memories, warnings and help from neighbors in Mason City.
Sources: FEMA National Risk Index v1.20 (December 2025), census-tract table, combined by where Mason City’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.