3 flood insurance claims·$19,821 paid·1 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 Johnson 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 and general flooding events shape the primary flood risks in Johnson County, Illinois. Over the last 30 years, recorded events include 14 flash flood events and 12 general flood events, which resulted in 1 death.
Recent flooding has been driven by slow-moving storm complexes and heavy rainfall systems moving along stalled frontal boundaries. For example, a major severe weather outbreak brought flooding to the region on May 8, 2024, while earlier events included heavy rains and isolated flash flooding on February 17, 2022, and slow-moving thunderstorms with high rainfall rates on August 12, 2020.
National Flood Insurance Program records show claims filed in both moderate-to-low risk and high-risk zones. Properties located in Zone X recorded 2 claims with an average payout of $7,527 and an average recorded water depth of 1 inch. Properties located in Zone A recorded 1 claim with an average payout of $4,767 and an average recorded water depth of 0 inches. Homeowners and real estate agents in both designated high-risk and moderate-to-low risk zones should review these historical claim records and local flood hazards when assessing property vulnerability.
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 1 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.
9 NOAA storm reports from Johnson County describe what happened, in the words of the forecasters who covered it. Read the Illinois flood stories →
7 federal disaster declarations since 1973, 1 of them floods, coastal storms or hurricanes.
| Disaster | Began |
|---|---|
| Severe Winter Storm | Jan 26, 2009 |
| Hurricane Katrina Evacuation | Aug 29, 2005 |
| Record/near Record Snow | Dec 21, 2004 |
| Severe Storms, Tornadoes And Flooding | Apr 21, 2002 |
| Severe Storms & Flooding | Apr 26, 1973 |
Weather and water disasters only; most recent first. Source: OpenFEMA Disaster Declarations.
26 since 1996: 14 flash floods and 12 river or area floods.
| Event | Date | Damage |
|---|---|---|
| Flood | May 8, 2024 | — |
| Flash Flood | Feb 17, 2022 | — |
| Flood | Aug 12, 2020 | — |
| Flood | Jul 7, 2016 | $15,000 · 1 killed |
| Flood | Jul 7, 2016 | — |
| Flood | Dec 21, 2013 | — |
| Flood | Apr 24, 2011 | $10,000 |
| Flood | May 1, 2011 | $120,000 |
— = no damage estimate in the record. Source: NOAA Storm Events Database.
Flood · May 8, 2024. A major outbreak of severe weather occurred on the 8th for the Quad State region. On the synoptic scale, a longwave trough was centered across the Rockies with deep-layer southwesterly flow from the Southern Plains to the Ohio Valley. A 110 kt upper jet extended from northern KS to IA while a 60 kt mid-level jet was positioned across northern MZ into IA. Surface low pressure near the MZ/KS border lifted to St. Lou…
Flash Flood · Feb 17, 2022. Several rounds of heavy rain and thunderstorms moved across the region on the 17th. Two to four inches were common, which resulted in isolated flash flooding and more widespread flooding of rivers. The heavy rain occurred ahead of a cold front as it entered southeast Missouri and southern Illinois from the northwest. Weak waves of low pressure moved northeast along the front. A strong 850 mb jet up to 60 to 70 kno…
Flood · Aug 12, 2020. Showers and thunderstorms increased in coverage and intensity through the day as daytime heating destabilized the atmosphere. The slow-moving storms occurred near a stalled frontal boundary that extended from northeast Missouri across southern Illinois to central Kentucky. Precipitable water values were near two inches. As a result, rainfall rates in thunderstorms were as much as two to three inches per hour.
Flood · Jul 7, 2016. A developing line of thunderstorms moved east-southeast across southern Illinois during the late morning and early afternoon hours. The storms moved through a moist and unstable environment ahead of a 500 mb shortwave trough over the mid and upper Mississippi Valley. A west to southwest flow of very moist air at 850 mb averaged from 20 to 30 knots. A few isolated storms produced damaging wind.
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 Johnson 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.