Enter any address in Johnson County, Illinois to see its FEMA flood zone
Flash flooding from heavy rainfall events is the dominant flood character in Johnson County, Illinois. Between 2000 and 2020, NOAA Storm Events data recorded 14 flash flood events and 12 flood events. Recent examples include a major outbreak of severe weather on May 8, 2024, and widespread flooding of rivers following heavy rain on February 17, 2022.
NFIP claims data indicates that properties in Zone A and Zone X have experienced flooding. Claims in Zone X, for instance, averaged $7,527 in payouts with an average water depth of 0.5 feet. Homeowners in areas prone to flash flooding, as well as those in or near designated flood zones, should pay close attention to flood risk.
Summary generated from NOAA storm narratives and NFIP claim data for this county. Not predictive.
9 NOAA storm reports from this county describe what happened, in the words of the meteorologists who were there.
Johnson County, Illinois has recorded 26 flood-related events since 1996 according to NOAA's Storm Events Database, including 14 flash floods and 12 river or area floods. The county has received 7 federal disaster declarations, 1 of which involved flooding or coastal storms. Enter any address above to check its FEMA flood zone designation.
FEMA Disaster Declarations (1973–2020)
Source: OpenFEMA Disaster Declarations Summaries.
| Declaration | Type | Date |
|---|---|---|
| Covid-19 | Biological | Jan 20, 2020 |
| Covid-19 Pandemic | Biological | Jan 20, 2020 |
| Severe Winter Storm | Severe Storm | Jan 26, 2009 |
| Hurricane Katrina Evacuation | Hurricane | Aug 29, 2005 |
| Record/near Record Snow | Snowstorm | Dec 21, 2004 |
| Severe Storms, Tornadoes And Flooding | Tornado | Apr 21, 2002 |
| Severe Storms & Flooding | Flood | Apr 26, 1973 |
NOAA Storm Events Database (1996–2025)
Source: NOAA National Weather Service Storm Events Database.
| Type | Date | Damage |
|---|---|---|
| Flood | May 8, 2024 | 0.00K |
| Flash Flood | Feb 17, 2022 | 0.00K |
| Flood | Aug 12, 2020 | 0.00K |
| Flood | Jul 7, 2016 | 15.00K (1 deaths) |
| Flood | Jul 7, 2016 | 0.00K |
| Flood | Dec 21, 2013 | 0.00K |
| Flood | Apr 24, 2011 | 10.00K |
| Flood | May 1, 2011 | 120.00K |
| Flood | Mar 18, 2008 | 1.60M |
| Flash Flood | Apr 3, 2008 | 0.00K |
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 bord...
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 je...
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 i...
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.
Flood — Jul 7, 2016
Isolated flash flooding occurred during the evening of July 6. A slow-moving thunderstorm complex backed slowly southwestward across western Kentucky and southern Illinois. The complex of storms was associated with a small 500 mb shortwave that moved east across western Kentucky late at night. The storms were fed by a very moist southwest wind flow around 30 knots at 850 mb. Precipitable water ...
Source: NOAA National Weather Service Storm Events Database.
Source: OpenFEMA NFIP Individual Claims (2.25M records analyzed).
FEMA assigns flood zone designations to areas in Johnson County, Illinois:
AE High Risk — 1% annual chance of flooding. Insurance required.
VE Very High Risk — Coastal flooding with wave action.
X (Shaded) Moderate Risk — 500-year floodplain.
X Low Risk — Outside major floodplains.
Properties in Johnson County, Illinois that are in FEMA-designated Special Flood Hazard Areas (zones A and V) with federally backed mortgages are required to carry flood insurance.
Even outside high-risk zones, flood insurance is recommended. From 2014 to 2024, nearly one-third of NFIP claims came from outside the high-risk Special Flood Hazard Area.
Visit FloodSmart.gov to find an agent and get a quote.