FEMA expects more hazard damage per building in North Sioux City than in 89% of U.S. towns, mostly from river and rain flooding
On FEMA’s National Risk Index, North Sioux City gets a D for hazard risk: higher expected damage per building than 89% of U.S. towns, #33 of 35 in South Dakota. Most of that expected damage is river and rain flooding (75%), then tornadoes (14%). Flood insurance has paid 12 claims 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 North 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
Wildfire
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 North Sioux City’s grade
River and rain flooding is 75% of the building damage FEMA expects in North Sioux City, and North Sioux City’s rate of river and rain flooding damage is in the top 9% of U.S. census tracts. Tornadoes add 14%, at a rate in the top 1% of U.S. census tracts.
D #33 of 35 in South Dakota; higher expected damage per building than 89% of U.S. towns (21,298).
North Sioux City’s residents live in 2 census tracts; FEMA’s figures are combined by where they live.
The typical South Dakota town has higher expected damage than 58% of U.S. towns; within the state, North Sioux City has more expected damage per building than 94% of South Dakota towns.
In dollars, FEMA expects about $3.1M a year in losses across North Sioux City: $2.4M to buildings, the rest to people and crops.
Does North Sioux City flood? Sometimes: 12 flood claims since 2010
Every paid claim on a federal flood insurance policy in North Sioux City, from FEMA’s records: 7.3 per 1,000 homes, more than 68% of the 13,809 U.S. towns with a flood insurance record.
- The Late spring storms6 claims · $42K
- The June Midwest Flooding4 claims · $1.3M
North 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: Union County.2 federal disasters brought FEMA money to North Sioux City
Disasters that paid out in North Sioux City itself (aid to households or repair grants to the City of North Sioux City), newest first, with that year’s flood claims.
- 2024Severe Storms, Straight-line Winds, and Flooding142 households applied for aid$1.8M aid approved4 flood claims paid that year
- 2011Flooding168 households applied for aid$408K aid approved6 flood claims paid that year
Union County has had 16 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 North Sioux City after a storm or flood belong in the town’s history. Add one, or share what you remember below.
Add to the North Sioux City archive →North Sioux City and its neighbors
North Sioux City is 2nd of the 4 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 |
|---|---|---|---|
| Sioux City | C+more damage than 58% | river and rain flooding | 152 |
| 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 North 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.
- Clear dead leaves and brush within 5 feet of the house.
- Sign up for local alerts and know two ways out.
- Keep N95 masks for smoky days.
- 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 North Sioux City
Is North Sioux City at risk for natural disasters?
On FEMA’s National Risk Index, North Sioux City has higher expected damage per building than 89% of U.S. towns: D for hazard risk, #33 of 35 in South Dakota. Most of the expected damage is river and rain flooding (75%) and tornadoes (14%). This is FEMA’s model of an average year for today’s buildings, not a forecast.
Does North Sioux City flood?
Flood insurance has paid 12 claims in North Sioux City since 2010, $1.3M in all, or 7.3 per 1,000 homes, more than 68% of U.S. towns with a flood insurance record. The most claims came from Late spring storms (6).
Is North 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 Union County, 26% of homes in mapped flood zones carry federal flood insurance, and 2.5% of all homes do.
How much is flood insurance in North Sioux City?
FEMA’s Community Rating System list shows no discount for North 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 North Sioux City?
By FEMA money that reached North Sioux City, Severe Storms, Straight-line Winds, and Flooding (2024): 142 households applied for aid, $1.8M approved. By flood claims, Late spring storms: 6 paid, $42K.
Is North Sioux City at risk from river and rain flooding?
It is the largest share of the building damage FEMA expects here (75%), and North Sioux City’s rate for it is in the top 9% of U.S. census tracts.
Storm stories
Memories, warnings and help from neighbors in North Sioux City.
Sources: FEMA National Risk Index v1.20 (December 2025), census-tract table, combined by where North 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.