13 flood insurance claims·$261,523 paid
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 Jefferson County, Illinois. 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 from summer thunderstorms dominates the flood risk profile in Jefferson County, Illinois, accounting for 34 flash flood events compared to 15 general flood events over the last 30 years, with general floods resulting in 3 deaths.
Recent history illustrates these local hazards. On July 16, 2024, extreme rainfall totals of 3 to 6 inches caused extensive street flooding in Mount Vernon and contributed to a secondary dam failure following heavy rains in neighboring areas. Later that summer on August 1, 2024, a robust squall line swept through the region, bringing scattered showers and severe wind damage along the I-64 corridor.
Federal insurance claims data shows that properties in high-risk Special Flood Hazard Areas—specifically Zone A—face the most frequent impacts, with 10 recorded claims averaging $22,462 in payouts and an average recorded water depth of 5 inches. However, risk extends beyond designated high-risk zones, as demonstrated by 2 claims in Zone X averaging $28,165 with an average water depth of 0 inches, and 1 claim in shaded Zone X averaging $3,032 with an average water depth of 1 inch. Homeowners, journalists, and real estate agents should pay the closest attention to properties located within Zone A, while remaining aware that moderate- and low-risk zones also experience damaging water accumulation.
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 4 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 2018, with 5 claims and $134,568 paid.
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.
21 NOAA storm reports from Jefferson County describe what happened, in the words of the forecasters who covered it. Read the Illinois flood stories →
5 federal disaster declarations since 2002.
| Disaster | Began |
|---|---|
| Severe Storms And Flooding | Apr 19, 2011 |
| Hurricane Katrina Evacuation | Aug 29, 2005 |
| Severe Storms, Tornadoes And Flooding | Apr 21, 2002 |
Weather and water disasters only; most recent first. Source: OpenFEMA Disaster Declarations.
49 since 1996: 34 flash floods and 15 river or area floods.
| Event | Date | Damage |
|---|---|---|
| Flood | Jul 16, 2024 | — |
| Flash Flood | Jul 16, 2024 | — |
| Flood | Aug 1, 2024 | — |
| Flash Flood | Aug 29, 2022 | $10,000 |
| Flash Flood | Jul 26, 2022 | — |
| Flood | Sep 4, 2022 | — |
| Flood | Jul 16, 2021 | $30,000 · 1 killed |
| Flash Flood | Mar 19, 2020 | — |
— = no damage estimate in the record. Source: NOAA Storm Events Database.
Flood · Jul 16, 2024. Extreme rainfall totals occurred during the morning of the 16th in and around Nashville, Illinois, just northwest of the Quad State region, which resulted in a secondary dam failure. Neighboring portions of Jefferson and Perry Counties received 3-6 and 2-5 inches, respectively. Extensive street flooding occurred in Mount Vernon, while some roads north of Tamaroa flooded for the second time within a week. Through t…
Flash Flood · Jul 16, 2024. Extreme rainfall totals occurred during the morning of the 16th in and around Nashville, Illinois, just northwest of the Quad State region, which resulted in a secondary dam failure. Neighboring portions of Jefferson and Perry Counties received 3-6 and 2-5 inches, respectively. Extensive street flooding occurred in Mount Vernon, while some roads north of Tamaroa flooded for the second time within a week. Through t…
Flood · Aug 1, 2024. A robust squall line swept through the I-64 corridor of Southern Illinois during the early afternoon hours on the 1st. Numerous wind damage reports were received, primarily in Wayne, Hamilton, and White Counties with many trees and powerlines damaged along with several farm structures. Utility data indicated that roughly half of Wayne County lost power with this storm line. MLCAPE values were approximately 3000 J/…
Flash Flood · Aug 29, 2022. An isolated severe thunderstorm drifted slowly over west central Hamilton County, producing large hail. This storm and other scattered thunderstorms developed during the heat of the day ahead of a cold front. Some of the storms produced torrential rain, which resulted in an isolated flash flood event. The cold front trailed southwest from a low pressure center over the Great Lakes region across northern Illinois a…
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 Jefferson 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.