Home›States›Nebraska›Sioux County
FEMA flood zones · Nebraska

Sioux County, Nebraska Flood Zone Map

2 federal flood & hurricane disasters

Less than 1% of Sioux County’s area is in FEMA’s high-risk flood zones.

Share of the whole county outline, rivers and lakes included; parts FEMA hasn’t mapped count as zero.

Coastal high risk (V, VE)FloodwayHigh risk (A, AE)Moderate (X, 500-year)Minimal (X)Undetermined (D)

Shaded areas are FEMA’s mapped flood hazard zones in and around Sioux County, Nebraska. Zoomed out they are simplified; at street level the map switches to FEMA’s exact layer. Tap anywhere to check that spot, or search an address above.

Federal disasters

13 federal disaster declarations since 1991, 2 of them floods, coastal storms or hurricanes.

DisasterBegan
Severe Winter Storm And Straight-line WindsApr 6, 2024
Severe Winter Storm, Straight-line Winds, And FloodingMar 9, 2019
Severe Storms, Tornadoes, And Straight-line WindsJun 12, 2017
Severe Storms, Tornadoes, Straight-line Winds, And FloodingMay 6, 2015
Severe Storms, Winter Storms, Tornadoes And FloodingOct 2, 2013
Region 23 Fire ComplexAug 30, 2012
Severe Storms And FloodingJun 1, 2010
Sioux County Fire ComplexJul 28, 2006

Weather and water disasters only; most recent first. Source: OpenFEMA Disaster Declarations.

Recorded flood events

6 since 1996: 6 flash floods.

EventDateDamage
Flash FloodJul 12, 2018—
Flash FloodJun 10, 2015—
Flash FloodJun 7, 2010—
Flash FloodJul 11, 2009—
Flash FloodJul 2, 2009—
Flash FloodJun 18, 2008—

— = no damage estimate in the record. Source: NOAA Storm Events Database.

From the storm reports

Flash Flood · Jul 12, 2018. Torrential rainfall from slow-moving thunderstorms produced localized flash flooding in southwest Sioux County.

Flash Flood · Jun 10, 2015. Afternoon thunderstorms over Sioux County produced very heavy rain and large hail.

Flash Flood · Jun 7, 2010. Moist southerly winds brought 50 to mid 60 degree dew points into the area. Due to so much moisture present, low status formed and lasted through the early afternoon. The stratus caused the atmosphere to remain stable through the early afternoon until the stratus began to clear out. With the moisture still present during the afternoon and a strong jet stream overhead, thunderstorms that former over the higher terr…

Flash Flood · Jul 11, 2009. A couple of storms produced hail and strong winds over parts of the western Nebraska panhandle.

National Weather Service narratives, lightly trimmed. Source: NOAA Storm Events Database.

The zones you’ll see on the map

Every colour on the map above is a place on this drawing: where the ground sits relative to the flood FEMA plans for.

Cross-section of a river floodplainDiagram: a river valley. The floodway is the channel and the land beside it; the 1%-annual-chance flood surface (the base flood elevation) covers the valley floor as zone A or AE; a narrow band higher up is shaded X, the 0.2% floodplain; higher ground is X.0.2% CHANCE A YEAR (500-YEAR)BASE FLOOD ELEVATION · 1% A YEARXAEFloodwayAEX
  1. A / AE Inside the 1%-a-year floodplain: about a 26% chance of flooding over a 30-year mortgage. AE has a mapped base flood elevation; plain A does not.
  2. Floodway The channel and the land beside it that has to be kept clear enough to carry the flood. Building here is tightly limited.
  3. X shaded The 0.2% (500-year) floodplain, plus some levee-protected and very shallow flood areas.
  4. X Outside both lines. No federal requirement to insure, which is not the same as no risk.

Every flood zone code explained →

Flood insurance in Sioux County

If a building in Sioux County is in a high-risk zone (A or V) and its mortgage comes from a federally regulated or insured lender, or is federally backed, flood insurance is required.

Outside those zones it is optional, and often worth having: from 2014 to 2024 nearly one-third of NFIP claims came from outside the high-risk Special Flood Hazard Area. Since Risk Rating 2.0, NFIP premiums are set for each building, so the only reliable price is a quote: FloodSmart.gov or a local agent.