13 flood insurance claims·$31,395 paid·4 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 Grundy 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.
Grundy County experiences a flood risk profile dominated by riverine floods and flash flooding driven by summer thunderstorms. Over the last 30 years, the NOAA Storm Events Database has recorded 36 flood events and 20 flash flood events.
Recent historic events illustrate this pattern. In May 2024, slow-moving thunderstorms driven by a low-pressure system dropped 2 to 4 inches of rainfall, resulting in flash flooding across the area. Similarly, in June 2020, convection along a surface boundary combined with subsequent shortwave activity produced localized heavy rainfall and overnight flooding.
National Flood Insurance Program records indicate that claims have been filed across multiple zones, with Zone A recording 9 claims averaging a payout of $2,942 and an average recorded water depth of 17 inches. Zone X recorded 2 claims with an average payout of $7,361 and an average recorded water depth of 12 inches, while Zone UNKNOWN recorded 2 claims with an average payout of $499 and an average water depth of 1 inch. Property owners in Zone A and Zone X should pay the closest attention to these historical flood and flash flood patterns.
Summary written from NOAA storm reports and NFIP claims for this county. Not a prediction.
In flood insurance claims here that reported a flood depth, the average was 12 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 2013, with 5 claims and $12,376 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.
50 NOAA storm reports from Grundy County describe what happened, in the words of the forecasters who covered it. Read the Iowa flood stories →
15 federal disaster declarations since 1969, 4 of them floods, coastal storms or hurricanes.
| Disaster | Began |
|---|---|
| Severe Storms | Aug 10, 2020 |
| Severe Storms, Tornadoes, Straight-line Winds, And Flooding | Jun 26, 2014 |
| Severe Storms, Tornadoes, And Flooding | Jun 21, 2013 |
| Severe Storms, Tornadoes, And Flooding | May 19, 2013 |
| Severe Storms, Tornadoes, And Flooding | May 25, 2008 |
| Severe Winter Storms | Feb 23, 2007 |
| Hurricane Katrina Evacuation | Aug 29, 2005 |
| Severe Storms, Tornadoes, And Flooding | May 19, 2004 |
Weather and water disasters only; most recent first. Source: OpenFEMA Disaster Declarations.
56 since 1996: 20 flash floods and 36 river or area floods.
| Event | Date | Damage |
|---|---|---|
| Flash Flood | May 21, 2024 | — |
| Flood | Jun 22, 2020 | — |
| Flood | Mar 14, 2019 | $100,000 |
| Flood | Oct 1, 2018 | — |
| Flood | Jul 1, 2018 | $100,000 |
| Flood | Aug 28, 2015 | $100,000 |
| Flash Flood | Aug 28, 2015 | $10,000 |
| Flash Flood | Aug 28, 2015 | $100,000 |
— = no damage estimate in the record. Source: NOAA Storm Events Database.
Flash Flood · May 21, 2024. PLEASE NOTE, for tornadoes, please see separate Storm Data entry for May 21st. ||Multiple rounds of thunderstorms brought torrential rainfall, damaging winds, hail and destructive tornadoes to the state. These thunderstorms were the result of a low pressure system which lifted north into the area on the night of May 20th, 2024, producing slow moving storms that dropped 2 to 4 inches of rainfall. This resulted in f…
Flood · Jun 22, 2020. A surface low to the northwest of Iowa allowed for convection to develop in the warm sector and along the surface boundary as it pushed across northern Iowa through the afternoon and evening of the 21st. These storms caused damaging winds and large hail across northern and central Iowa. Localized areas received heavy rain that resulted in flooding overnight. Another shortwave embedded within the parent longwave tr…
Flood · Mar 14, 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…
Flood · Oct 1, 2018. A frontal boundary resided predominantly right along the Iowa-Missouri border and remained relatively stationary throughout the event. Beginning on September 30th, 850mb flow rode over the front and helped initiated elevated showers and weak storms that persisted (scattered in nature) form the late afternoon of the 30th through the late afternoon on the 1st. While no severe weather was recorded, weak instability (…
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 Grundy 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.