Photo: w_lemay · CC BY-SA 2.0Sioux City’s building-damage rate from tornadoes is in the top 2% of U.S. census tracts
On FEMA’s National Risk Index, Sioux City gets a C+ for hazard risk: higher expected damage per building than 58% of U.S. towns, #97 of 140 in Iowa. Most of that expected damage is river and rain flooding (63%), then tornadoes (22%). Flood insurance has paid 152 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 Sioux City’s natural hazards
From FEMA’s model and FEMA’s records, below.
What Sioux 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
Hail
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 Sioux City’s grade
River and rain flooding is 63% of the building damage FEMA expects in Sioux City, and Sioux City’s rate of river and rain flooding damage is higher than 58% of U.S. census tracts. Tornadoes add 22%, at a rate in the top 2% of U.S. census tracts.
C+ #97 of 140 in Iowa; higher expected damage per building than 58% of U.S. towns (21,298).
Sioux City’s residents live in 25 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, Sioux City has more expected damage per building than 69% of Iowa towns.
In dollars, FEMA expects about $35.4M a year in losses across Sioux City: $19.1M to buildings, the rest to people and crops.
Does Sioux City flood? Yes: 152 flood claims since 1978
Every paid claim on a federal flood insurance policy in Sioux City, from FEMA’s records: 4.3 per 1,000 homes, more than 57% of the 13,809 U.S. towns with a flood insurance record.
- The June Midwest Flooding8 claims · $457K
- The March 2019 Midwest Flooding1 claim · $13K
- The Late spring storms1 claim · $2K
Sioux 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: Woodbury County.7 federal disasters brought FEMA money to Sioux City
Disasters that paid out in Sioux City itself (aid to households or repair grants to the City of Sioux City), newest first, with that year’s flood claims.
- 2024Severe Storms, Flooding, Straight-line Winds, and Tornadoes212 households applied for aid$2.4M aid approved$2.4M to the City of Sioux City for repairs8 flood claims paid that year
- 2019Severe Storms and Flooding327 households applied for aid$358K aid approved$8.0M to the City of Sioux City for repairs1 flood claim paid that year
- 2014Severe Storms, Tornadoes, Straight-line Winds, and Flooding$298K to the City of Sioux City for repairs3 flood claims paid that year
- 2011Flooding1 households applied for aid$2.6M to the City of Sioux City for repairs1 flood claim paid that year
- 2009Severe Winter Storms and Snowstorm$186K to the City of Sioux City for repairs
- 2007Snow$103K to the City of Sioux City for repairs
Show all 7
- 1999Severe Storms and Flooding$223K to the City of Sioux City for repairs
Woodbury County has had 15 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 Sioux City after a storm or flood belong in the town’s history. Add one, or share what you remember below.
Add to the Sioux City archive →Sioux City and its neighbors
Sioux City is 2nd 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 |
|---|---|---|---|
| Sergeant Bluff | B+less damage than 69% | river and rain flooding | — |
| Sioux City | C+more damage than 58% | river and rain flooding | 152 |
| South Sioux City | C+more damage than 60% | river and rain flooding | 20 |
| Dakota City | C+more damage than 61% | river and rain flooding | 5 |
| North Sioux City | Dmore damage than 89% | river and rain flooding | 12 |
| Big Sioux Township | Dmore damage than 91% | river and rain flooding | 27 |
| Dakota Dunes | Dmore damage than 91% | 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 Sioux 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.
- Park in a garage or under cover when storms are forecast.
- Stay away from windows while it falls.
- Photograph roof and car damage for your insurer.
- 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 Sioux City
Is Sioux City at risk for natural disasters?
On FEMA’s National Risk Index, Sioux City has higher expected damage per building than 58% of U.S. towns: C+ for hazard risk, #97 of 140 in Iowa. Most of the expected damage is river and rain flooding (63%) and tornadoes (22%). This is FEMA’s model of an average year for today’s buildings, not a forecast.
Does Sioux City flood?
Flood insurance has paid 152 claims in Sioux City since 1978, $1.3M in all, or 4.3 per 1,000 homes, more than 57% of U.S. towns with a flood insurance record. The most claims came from June Midwest Flooding (8).
Is Sioux 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 Woodbury County, 16% of homes in mapped flood zones carry federal flood insurance, and 0.5% of all homes do.
How much is flood insurance in Sioux City?
FEMA’s Community Rating System list shows no discount for Sioux 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 Sioux City?
By FEMA money that reached Sioux City, Severe Storms and Flooding (2019): 327 households applied for aid, $358K approved, and $8.0M to the City of Sioux City for repairs. By flood claims, June Midwest Flooding: 8 paid, $457K.
Is Sioux City at risk from river and rain flooding?
It is the largest share of the building damage FEMA expects here (63%), and Sioux City’s rate for it is higher than 58% of U.S. census tracts.
Storm stories
Memories, warnings and help from neighbors in Sioux City.
Sources: FEMA National Risk Index v1.20 (December 2025), census-tract table, combined by where Sioux 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.