57 flood insurance claims·$337,593 paid·7 federal flood & hurricane disasters
Share of the whole county outline, rivers and lakes included; parts FEMA hasn’t mapped count as zero.
Shaded areas are FEMA’s mapped flood hazard zones in and around Cass County, Iowa. 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.
Flash flooding and river flooding from heavy rainfall dominate Cass County, with the NOAA Storm Events Database recording 34 flash flood events and 17 flood events over the last 30 years.
Spring flooding occurred in March 2019 when a deep winter snowpack, frozen ground, and heavy rain combined to cause rapid runoff into river systems. Later that year, heavy rainfall and high moisture transport produced flash flooding events in May 2019.
Properties located in FEMA Zone A should pay the most attention to flood risk, as this zone accounts for the majority of NFIP claims in the county with 38 claims averaging $8,304 per payout and an average recorded water depth of 4 inches. Additional claims are distributed across unknown zones, Zone X, and shaded and unshaded Zone X designations, where average payouts ranged from $0 to $5,826 and average recorded water depths were between 0 and 3 inches.
Summary written from NOAA storm reports and NFIP claims for this county. Not a prediction.
5% of Cass County’s flood insurance claims were on properties rated outside FEMA’s high-risk zones.
40 NFIP claims with a recorded rated flood zone, 1978 to date. The zone is the one FEMA used to rate that policy, which may not match today’s map. Source: OpenFEMA NFIP claims.
In flood insurance claims here that reported a flood depth, the average was 3 inches.
Drawn to scale against an 80-inch door. Even a few inches soaks flooring, the bottom of the drywall and anything plugged in near the floor.
Average of the depths reported on claims (zero and implausible values left out); FEMA’s record doesn’t say exactly where each depth was measured. Source: OpenFEMA NFIP claims.
The worst year was 1998, with 21 claims and $134,524 paid, the year of Severe Storms, Tornadoes and Flooding.
Bar height is scaled by square root so ordinary years stay visible next to the worst one. NFIP claims by year of loss. Source: OpenFEMA.
45 NOAA storm reports from Cass County describe what happened, in the words of the forecasters who covered it. Read the Iowa flood stories →
19 federal disaster declarations since 1965, 7 of them floods, coastal storms or hurricanes.
| Disaster | Began |
|---|---|
| Severe Storms, Straight-line Winds, And Tornadoes | Dec 15, 2021 |
| Severe Storms And Flooding | Mar 12, 2019 |
| Severe Winter Storm | Jan 19, 2010 |
| Severe Winter Storms And Snowstorm | Dec 23, 2009 |
| Severe Storms, Tornadoes, And Flooding | May 25, 2008 |
| Severe Storms, Flooding, And Tornadoes | May 5, 2007 |
| Snow | Feb 28, 2007 |
| Hurricane Katrina Evacuation | Aug 29, 2005 |
Weather and water disasters only; most recent first. Source: OpenFEMA Disaster Declarations.
51 since 1996: 34 flash floods and 17 river or area floods.
| Event | Date | Damage |
|---|---|---|
| Flash Flood | Sep 24, 2019 | $5,000 |
| Flash Flood | May 24, 2019 | $50,000 |
| Flash Flood | May 24, 2019 | $20,000 |
| Flood | Mar 14, 2019 | — |
| Flood | Mar 13, 2019 | $10,000 |
| Flash Flood | May 26, 2016 | $25,000 |
| Flash Flood | May 11, 2014 | $100,000 |
| Flash Flood | Sep 9, 2014 | $15,000 |
— = no damage estimate in the record. Source: NOAA Storm Events Database.
Flash Flood · Sep 24, 2019. A relatively routine setup for strong to severe storms took place on the 24th of September. A cold front entered the state from the northwest during the late afternoon and early evening hours, entering an environment with strong low level moisture inflow, SBCAPE values in excess of 2000 J/kg, and effective bulk shear around 40 kts. With frontal forcing and the aforementioned conditions, storms were of little quest…
Flash Flood · May 24, 2019. The setup over Iowa was primed for a heavy rainfall event for a few reasons, including persistent SW 500 mb flow, a strong and SW oriented 850 mb jet, strong low level moisture transport, and elevated CAPE around 1000-2000 J/kg. Precipitable water values, given the strong moisture transport into the area, rose into the neighborhood of 1.7 inches throughout the event as well. While effective bulk shear values were…
Flood · Mar 14, 2019. Higher than average snowfall through the winter created a wet snowpack across much of Iowa which was still present into early March. A large storm system impacted the region through the middle of March which brought heavy rain and warm temperatures to the state. This system allowed much of the snowpack to melt across the state within a few days to a week. This heavy rain fell on frozen ground allowing nearly all o…
Flood · Mar 13, 2019. Reports from the 13h through the 19th in this entry. ||A relatively deep and widespread snowpack existed across the region during early to mid March. Many areas in central and northern Iowa had around a foot to two feet of snow on the ground, along with many areas in upstream river basins in Minnesota and the Dakotas having similar or deeper snowpacks on the ground. Additionally, with the below normal temperatures…
National Weather Service narratives, lightly trimmed. Source: NOAA Storm Events Database.
Every colour on the map above is a place on this drawing: where the ground sits relative to the flood FEMA plans for.
If a building in Cass 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.