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B+Hazard risk
Natural hazards in Thornton · FEMA

FEMA puts Thornton’s expected hazard damage per building below that of 65% of U.S. towns, mostly from river and rain flooding

On FEMA’s National Risk Index, Thornton gets a B+ for hazard risk: lower expected damage per building than 65% of U.S. towns. Most of that expected damage is river and rain flooding (81%), then tornadoes (14%). Flood insurance has paid 4 claims here since 1980.

River and rain flooding 81%Tornadoes 14%Earthquakes 4%

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

less than 65%of U.S. townsLess damageMoreExpected yearly damage per dollar of building, vs. the 21,298 U.S. towns we grade
Hazard risk
B+
in Illinois · lower than 65% of U.S. towns
Main hazard
River and rain flooding
81% of expected building damage
Flood claims
4
paid since 1980 · $20K
Disasters paid out here
10
of 21 declared for Cook County
By hazard

What Thornton 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

81%of expected building damage
About average · higher than 54% of U.S. census tracts
Recorded about 6 times a year in the area

Tornadoes

14%of expected building damage
Well above average · higher than 83% of U.S. census tracts
Smaller shares here
 Earthquakes Hail Ice storms Strong wind Winter storms Hurricanes Wildfire Cold waves Heat waves Landslides Lightning
FEMA models no building damage here
Coastal floodingAvalanchesTsunamisVolcanic activity
People, not buildings.Counting harm to people as well as buildings, FEMA’s model puts cold waves at 24% of Thornton’s expected losses. Cold waves do little damage to buildings (0.0%), so they aren’t part of the grade.

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.

Flood risk changes street by street. Check a specific address on FEMA’s flood map, and ask about flood insurance before you buy.
Hazard risk grade

What’s behind Thornton’s grade

River and rain flooding is 81% of the building damage FEMA expects in Thornton, and Thornton’s rate of river and rain flooding damage is higher than 54% of U.S. census tracts. Next is tornadoes at 14% (higher than 83% of U.S. census tracts).

Where Thornton sits
Thornton
Least damageMiddleMost damage

B+ lower expected damage per building than 65% of U.S. towns (21,298).

All of Thornton’s residents live in one census tract; the figures are that tract’s.

What drives the damage to buildings
River and rain flooding81%Tornadoes14%Earthquakes4%Everything else2%

In dollars, FEMA expects about $1.4M a year in losses across Thornton: $802K to buildings, the rest to people and crops.

Recent disaster.FEMA’s model looks at expected damage to the buildings standing today. After Severe Storms, Tornadoes, Straight-line Winds, and Floodng in 2024, FEMA took 103 aid registrations from Thornton addresses (the town has 891 homes).
Shared tract.All of Thornton’s 2,386 residents (2020 census) live in one census tract. FEMA publishes its model by tract, so the rate and the hazard mix are the tract’s. The flood claims below are the town’s own.
A shared figure. The grade describes the whole tract, not each street in it, and FEMA’s model is an average year for today’s buildings, not a record: the claims below are the record.

How TownRatings grades hazard risk →

Flood insurance claims

Does Thornton flood? Rarely: 4 flood claims since 1980

Every paid claim on a federal flood insurance policy in Thornton, from FEMA’s records: 4.5 per 1,000 homes, more than 58% of the 13,809 U.S. towns with a flood insurance record.

Paid flood claims, by year
1980: 1 claim1981: 0 claims1982: 2 claims1983: 0 claims1984: 0 claims1985: 0 claims1986: 0 claims1987: 0 claims1988: 0 claims1989: 0 claims1990: 0 claims1991: 0 claims1992: 0 claims1993: 0 claims1994: 0 claims1995: 0 claims1996: 0 claims1997: 0 claims1998: 0 claims1999: 0 claims2000: 0 claims2001: 0 claims2002: 0 claims2003: 0 claims2004: 0 claims2005: 0 claims2006: 0 claims2007: 0 claims2008: 0 claims2009: 0 claims2010: 0 claims2011: 0 claims2012: 0 claims2013: 1 claim2014: 0 claims2015: 0 claims2016: 0 claims2017: 0 claims2018: 0 claims2019: 0 claims2020: 0 claims2021: 0 claims2022: 0 claims2023: 0 claims2024: 0 claims2025: 0 claims2026: 0 claims198019822013
19802026
Biggest named events
  • The Mid-spring storms1 claim · $11K
4
paid claims since 1980
$20K
paid to owners
0
homes flooded more than once
$5K
average claim
of homes in flood zones are insured
of all homes are insured
No community discount

Thornton isn’t in FEMA’s Community Rating System, which cuts flood insurance up to 45% in towns that do extra flood-proofing.

Insurance rates: Cook County.
Disasters

10 federal disasters brought FEMA money to Thornton

Disasters that paid out in Thornton itself (aid to households or repair grants to the Village of Thornton), newest first, with that year’s flood claims.

  1. 2024Severe Storms, Tornadoes, Straight-line Winds, and Floodng103 households applied for aid$222K aid approved
  2. 2023Severe Storms and Flooding23 households applied for aid$47K aid approved
  3. 2023Severe Storms and Flooding81 households applied for aid$133K aid approved
  4. 2013Severe Storms, Straight-line Winds, and Flooding26 households applied for aid$54K aid approved1 flood claim paid that year
  5. 2011Severe Winter Storm and Snowstorm$8K to the Village of Thornton for repairs
  6. 2010Severe Storms and Flooding20 households applied for aid$32K aid approved
Show all 10
  1. 2008Severe Storms and Flooding71 households applied for aid$66K aid approved$10K to the Village of Thornton for repairs
  2. 2007Severe Storms and Flooding$5K to the Village of Thornton for repairs
  3. 2000Illinois Winter Snow Storms$3K to the Village of Thornton for repairs
  4. 1999Il-winter Storm 1/1/99$5K to the Village of Thornton for repairs
Disasters declared, by decade
Paid out in ThorntonCook County only

Cook County has had 21 natural disasters declared by the President since 1953, most often severe storms, then floods. Not counted: the 2005 Hurricane Katrina evacuee emergency, which covered counties that took in evacuees.

Were you here?

Old photos of Thornton after a storm or flood belong in the town’s history. Add one, or share what you remember below.

Add to the Thornton archive →
Next door

Thornton and its neighbors

Thornton has the lowest expected damage per building of the 6 graded towns here. Tap a town to see its hazards.

South Holland: hazard risk DHomewood: hazard risk C−Thornton Township: hazard risk DBloom Township: hazard risk CGlenwood: hazard risk C+South HollandHomewoodThornton TownshipBloom TownshipGlenwoodThornton
Lowest fifthSecondMiddleFourthHighest fifth
TownHazard riskMostly (buildings)Flood claims
ThorntonB+less damage than 65%river and rain flooding4
GlenwoodC+more damage than 61%river and rain flooding19
Bloom TownshipCmore damage than 66%river and rain flooding238
HomewoodC−more damage than 77%river and rain flooding49
Thornton TownshipDmore damage than 87%river and rain flooding2,023
South HollandDmore damage than 93%river and rain flooding494

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.

Be ready

Get ready for what Thornton faces

A short kit for the hazards that drive the building damage here, what to check before you buy, and where neighbors get alerts.

When the river rises
  • 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.
More from Ready.gov ↗
Tornado warnings
  • 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.
More from Ready.gov ↗
Before you buy or rent
  • 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.
When a storm is coming
Forecast and alertsWeather →911, the nearest ERSafety →

Know where neighbors sign up for alerts? Add it to the Handbook so everyone has it.

Questions about natural hazards in Thornton

Is Thornton at risk for natural disasters?

On FEMA’s National Risk Index, Thornton has lower expected damage per building than 65% of U.S. towns: B+ for hazard risk. Most of the expected damage is river and rain flooding (81%) and tornadoes (14%). The figures are for the one census tract the town shares with its neighbors. This is FEMA’s model of an average year for today’s buildings, not a forecast.

Does Thornton flood?

Flood insurance has paid 4 claims in Thornton since 1980, $20K in all, or 4.5 per 1,000 homes, more than 58% of U.S. towns with a flood insurance record. The most claims came from Mid-spring storms (1).

Is Thornton 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 Cook County, 32% of homes in mapped flood zones carry federal flood insurance, and 0.5% of all homes do.

How much is flood insurance in Thornton?

FEMA’s Community Rating System list shows no discount for Thornton’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 Thornton?

By FEMA money that reached Thornton, Severe Storms, Tornadoes, Straight-line Winds, and Floodng (2024): 103 households applied for aid, $222K approved. By flood claims, Mid-spring storms: 1 paid, $11K.

Is Thornton at risk from river and rain flooding?

It is the largest share of the building damage FEMA expects here (81%), and Thornton’s rate for it is higher than 54% of U.S. census tracts.

Storm stories

Memories, warnings and help from neighbors in Thornton.

Town Square →
Start the conversation

Sources: FEMA National Risk Index v1.20 (December 2025), census-tract table, combined by where Thornton’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.