Illinois floods
Every recorded flood since 1996 · 102 counties with a record
NOAA's Storm Events Database records 6,507 floods and flash floods in Illinois from 1996 through June 30, 2026, about 224 a year since 2000. The deadliest was the December 26, 2015 flash flood in Marion County: 6 deaths across 2 records. Illinois ranks 10th of 52 states and territories by count and 18th of 51 per square mile.
Floods in Illinois, 1996 to 2026
Flood records per year (NOAA Storm Events); 2026 to June 30, 2026.
- recorded, no damage figure
- under $1 million
- $1 million or more
- $10 million or more
- $100 million or more, or 10 deaths
- $1 billion or more, or 100 deaths
- a year's colour: its recorded damage or deaths
- a year with a death
- Records
- 6,5071996 to June 30, 2026
- A year since 2000
- 224average
- Deaths
- 6141 injuries
- Damage, 2025 dollars
- $3.4Bas filed
- Busiest year
- 2002413 records
Source: NOAA NCEI Storm Events Database, records through June 30, 2026; deaths and damage as filed, damage in 2025 dollars. Search the record at NCEI.
Are floods and flash floods common in Illinois?
Illinois averages about 224 floods and flash floods a year since 2000, 10th of 52 states and territories by count. The busiest year on record was 2002 (413). Per 10,000 square miles of land, Illinois records 1172 floods and flash floods since 1996, 18th of 51 states and territories by that measure.
Source: NOAA NCEI Storm Events Database, records since 1996, per 10,000 square miles of land area (Census Bureau 2024 Gazetteer; places under 1,000 square miles not ranked). Damage colours: Storm Events damage, 2025 dollars.
Which counties in Illinois have the most floods and flash floods?
Per square mile, Alexander County leads Illinois: 213 days with a flood since 1996, 904.9 per 1,000 square miles of land. By raw count, Cook County has the most flood records (423 since 1996); large counties collect more records simply by covering more ground, so the ranking counts days with a record per unit of area (a storm filed for several forecast zones adds several records but one day).
Source: NOAA NCEI Storm Events Database, days with a record in the county since 1996 per 1,000 square miles of land (Census Bureau 2024 Gazetteer); in brackets, the count of records.
When is flood season in Illinois?
42% of its floods and flash floods since 1996 fell in May and June. The busiest month is June (1,374 records).
The values, month by month
Jan 302 · Feb 375 · Mar 407 · Apr 675 · May 1,351 · Jun 1,374 · Jul 857 · Aug 550 · Sep 263 · Oct 125 · Nov 47 · Dec 181 (records).
Source: NOAA NCEI Storm Events Database, records by the month they began, since 1996.
What were the deadliest floods and flash floods in Illinois?
| Date | Record | Character | Killed | Injured | Damage |
|---|---|---|---|---|---|
| 2015-12-26 | Flash FloodVernon, Marion County One storm episode: 2 records in 2 places; the totals are the episode's. A prolonged period of rainfall occurred from the early morning hours of December 26th to the evening of December 28th. The heaviest rainfall occurred in a 50 to 75 mile wide swath from southwest Missouri through the Greater St. Louis Metropolitan Area and into central Illinois. Three day rainfall totals within this ... | 6 | 0 | – | |
| 2011-07-27 | Flash FloodEast Dubuque, Jo Daviess County One storm episode: 3 records in 3 places; the totals are the episode's. Hot and humid conditions prevailed across the region July 27, as a warm front lifted northward into northeast Iowa. Showers and thunderstorms developed along the Highway 20 corridor in Dubuque, Jo Daviess and Stephenson Counties during the early evening hours of July 27. They continued to redevelop and move over the ... | 5 | 0 | $10M | |
| 2015-12-27 | FloodSicily, Christian County One storm episode: 6 records in 6 places; the totals are the episode's. A multi-faceted storm system brought several periods of heavy rain to central and southeast Illinois from December 26th through 28th. The system began to spread rain into the region from the southwest during the early morning hours of Saturday, December 26th, with the rain continuing into Saturday night. By the ... | 4 | 0 | $9.0M | |
| 2000-08-07 | Flash FloodRobinson, Crawford County A cluster of thunderstorms persisted over mainly the far northern parts of the county into the overnight hours. Radar estimates indicated from 4 to over 5 inches of rain falling over a period of less than 6 hours. This resulted in flash flooding occurring in the far northwestern part of the county. A culvert went over ... | 3 | 0 | $1.7M | |
| 2008-09-13 | Flash FloodBryn Mawr, Cook County One storm episode: 6 records in 4 places; the totals are the episode's. A warm front moved across northern Illinois during the morning hours of September 13th as the remnants of tropical storm Lowell moved across the region. These two features combined to produce heavy rain and flash flooding across many areas of northern Illinois. | 2 | 3 | $56M | |
| 2008-03-18 | FloodDix, Jefferson County One storm episode: 15 records in 15 places; the totals are the episode's. Torrential rainfall amounts from 6 to 12 inches occurred over a two-day period, causing an historic flood event. A very slow-moving cold front over southwest Illinois and southeast Missouri provided the focus for prolonged heavy rainfall. A deep southwest wind flow brought subtropical moisture across the frontal zone. ... | 2 | 2 | $41M | |
| 1996-07-17 | Flash FloodCountywide, Will County | 2 | 0 | – | |
| 2024-07-14 | Flash FloodRockford, Winnebago County One storm episode: 2 records; the totals are the episode's. Thunderstorms developed during the evening of July 14th and continued into the early morning of July 15th, as they moved across all of northern and central Illinois. Nine tornadoes occurred, along with widespread wind damage. In the City of Chicago, there were 2,810 tree emergency calls and 1,430 calls for tree ... | 1 | 1 | $470K | |
| 2008-01-08 | FloodLodemia, Livingston County One storm episode: 5 records in 4 places; the totals are the episode's. Heavy rain fell during the morning hours of January 8th which caused siginficant flooding over many areas of east central Illinois. | 1 | 1 | $8.2M | |
| 2016-07-07 | FloodVienna, Johnson County Just northwest of Vienna, an elderly lady drowned after her vehicle was driven into a flooded creek. The 75-year-old woman died after her family drove off a section of the road that was covered in floodwater from Dutchman Creek. The vehicle was carried downstream. The other three individuals in the vehicle were ... | 1 | 1 | $18K |
Source: NOAA NCEI Storm Events Database: deaths direct and indirect, as filed by the National Weather Service, summed over each storm (one episode, or one named storm filed by several offices). Storm names from the titles of FEMA declarations that name the storm's counties.
The costliest floods and flash floods in Illinois
| Date | Record | Character | Killed | Injured | Damage |
|---|---|---|---|---|---|
| 2023-07-02 | Flash FloodEvanston, Cook County | 0 | 0 | $484M | |
| 2010-07-24 | FloodMunger, DuPage County One storm episode: 5 records in 4 places; the totals are the episode's. | 1 | 0 | $352M | |
| 2025-08-17 | Flash FloodHegewisch, Cook County One storm episode: 14 records in 5 places; the totals are the episode's. | 0 | 0 | $288M | |
| 2013-04-17 | Flash FloodSankoty, Peoria County One storm episode: 9 records in 8 places, 2013-04-17 to 2013-04-18; the totals are the episode's. | 0 | 2 | $276M | |
| 2011-06-17 | Flash FloodMeredosia, Morgan County One storm episode: 2 records in 2 places; the totals are the episode's. | 0 | 0 | $214M | |
| 2025-07-25 | Flash FloodBurr Ridge, Cook County One storm episode: 8 records in 5 places; the totals are the episode's. | 0 | 0 | $200M | |
| 2013-04-18 | Flash FloodLake Holiday, LaSalle County One storm episode: 6 records in 5 places; the totals are the episode's. | 1 | 0 | $151M | |
| 1996-07-17 | Flash FloodSouthern, Cook County | 0 | 0 | $84M |
Source: NOAA NCEI Storm Events Database: property and crop damage as estimated by the National Weather Service, in 2025 dollars.
Are floods and flash floods becoming more frequent in Illinois?
Illinois's count per decade against the whole country's, and its share. NOAA recorded every event type only from 1996, so earlier decades are not comparable; the share of the national total is the fairer comparison across decades.
| Decade | Illinois | United States | Illinois's share |
|---|---|---|---|
| 1996-99 | 569 | 20,986 | 2.7% |
| 2000s | 2,234 | 54,913 | 4.1% |
| 2010s | 2,529 | 68,322 | 3.7% |
| 2020-26 | 1,175 | 43,563 | 2.7% |
Source: NOAA NCEI Storm Events Database.
The most recent floods and flash floods in Illinois
| Date | Record | Character | Killed | Injured | Damage |
|---|---|---|---|---|---|
| 2026-06-27 | Flash FloodCentralia Municipal Airport, Marion County | 0 | 0 | $10K | |
| 2026-06-27 | Flash FloodXenia, Clay County | 0 | 0 | – | |
| 2026-06-27 | Flash FloodCharleston, Coles County | 0 | 0 | – | |
| 2026-06-27 | FloodCharleston, Coles County | 0 | 0 | – | |
| 2026-06-24 | FloodMetamora, Woodford County | 0 | 0 | – | |
| 2026-06-24 | FloodStreator Jct, Woodford County | 0 | 0 | – | |
| 2026-06-24 | FloodBolingbrook, Will County | 0 | 0 | – | |
| 2026-06-24 | FloodSouth Deering, Cook County | 0 | 0 | – | |
| 2026-06-24 | FloodRoseland, Cook County | 0 | 0 | – | |
| 2026-06-24 | FloodNaperville, DuPage County | 0 | 0 | – | |
| 2026-06-24 | FloodCrestwood, Cook County | 0 | 0 | – | |
| 2026-06-24 | FloodRiver Grove, Cook County | 0 | 0 | – |
Source: NOAA NCEI Storm Events Database, records through June 30, 2026; the newest months are revised by NCEI as reports arrive. Search the record at NCEI.
Federal disaster declarations for floods and flash floods in Illinois
FEMA has declared 44 disasters in Illinois for floods and flash floods, counting its incident type and declarations that name flood in the title (FEMA files most storm disasters under Severe Storm); 44 were major disasters, the latest on September 20, 2024.
| Declared | Number | Title | Areas named |
|---|---|---|---|
| 2024-09-20 | DR-4819 | Severe Storms, Tornadoes, Straight-Line Winds, and Floodng | 7 |
| 2023-11-20 | DR-4749 | Severe Storms and Flooding | 1 |
| 2023-08-15 | DR-4728 | Severe Storms and Flooding | 22 |
| 2022-10-14 | DR-4676 | Severe Storm and Flooding | 1 |
| 2019-09-19 | DR-4461 | Severe Storms and Flooding | 28 |
| 2013-05-10 | DR-4116 | Severe Storms, Straight-Line Winds, and Flooding | 47 |
| 2011-06-07 | DR-1991 | Severe Storms and Flooding | 21 |
| 2010-08-19 | DR-1935 | Severe Storms and Flooding | 11 |
| 2009-07-02 | DR-1850 | Severe Storms, Flooding, and Tornadoes | 8 |
| 2008-10-03 | DR-1800 | Severe Storms and Flooding | 16 |
| 2008-06-24 | DR-1771 | Severe Storms and Flooding | 25 |
| 2008-03-07 | DR-1747 | Severe Storms and Flooding | 2 |
Source: FEMA OpenFEMA Disaster Declarations Summaries (v2), through October 2, 2026. OpenFEMA dataset page.
Next
- Alexander County: the county's whole recordThe Illinois county with the most floods and flash floods per square mile
- Floods across the United StatesEvery state ranked, by year and month
- Every natural hazard in IllinoisTornadoes, floods, storms, heat and the federal declarations
- Severe thunderstorm wind in Illinois22,068 records
- Hail in Illinois12,331 records
- Winter storms in Illinois8,149 records