Delaware floods

Every recorded flood since 1996 · 3 counties with a record

NOAA's Storm Events Database records 615 floods and flash floods in Delaware from 1996 through June 30, 2026, about 21 a year since 2000. The deadliest was Hurricane Floyd (September 16, 1999) in New Castle County: 2 deaths, 2 injuries and $14.8 million in damage in 2025 dollars across 3 records. Delaware ranks 49th of 52 states and territories by count and 5th of 51 per square mile.

Floods in Delaware, 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: 6151996 to June 30, 2026
A year since 2000: 21average
Deaths: 412 injuries
Damage, 2025 dollars: $128Mas filed
Busiest year: 201748 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 Delaware?

Delaware averages about 21 floods and flash floods a year since 2000, 49th of 52 states and territories by count. The busiest year on record was 2017 (48). Per 10,000 square miles of land, Delaware records 3156 floods and flash floods since 1996, 5th 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 Delaware have the most floods and flash floods?

Per square mile, New Castle County leads Delaware: 205 days with a flood since 1996, 480.8 per 1,000 square miles of land. By raw count, New Castle County has the most flood records (278 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).

New Castle County 480.8 (278)
Sussex County 159.2 (258)
Kent County 112.6 (79)

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 Delaware?

Delaware's floods and flash floods by month. The busiest month is August (98 records).

The values, month by month

Jan 34 · Feb 32 · Mar 39 · Apr 24 · May 21 · Jun 79 · Jul 84 · Aug 98 · Sep 71 · Oct 75 · Nov 22 · Dec 36 (records).

Source: NOAA NCEI Storm Events Database, records by the month they began, since 1996.

What were the deadliest floods and flash floods in Delaware?

Delaware: the storms with the most deaths since 1996
Date	Record	Character	Killed	Injured	Damage
1999-09-16	Hurricane Floyd · Flash FloodCountywide, New Castle County One storm episode: 3 records in 3 places; the totals are the episode's. Hurricane Floyd battered Delaware (especially New Castle County) on September 16th and brought with it torrential rains and damaging winds. The hurricane caused widespread flash flooding as storm totals averaged around nine inches, most of which fell in a twelve hour period from the early morning through the afternoon ...		2	2	$15M
2011-08-27	Hurricane Irene · Flash FloodMilford Xrds, New Castle County Hurricane Irene produced heavy flooding rain, widespread tropical storm force wind gusts, a confirmed tornado near Lewes in Sussex County, moderate to severe coastal flooding and beach erosion and caused two flooding related deaths, forced evacuations near the coast over the weekend of August 27th and 28th in ...		2	0	–

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 Delaware

Delaware: the most damaging storms since 1993, 2025 dollars
Date	Record	Killed	Injured	Damage
2009-11-12	Coastal FloodSussex County · forecast zone Delaware Beaches One storm episode: 2 records; the totals are the episode's.	0	0	$62M
2003-09-15	Tropical Storm Henri · Flash FloodNorth Portion, New Castle County	0	1	$26M
1999-09-16	Hurricane Floyd · Flash FloodCountywide, New Castle County One storm episode: 3 records in 3 places; the totals are the episode's.	2	2	$15M
2012-10-30	Hurricane Sandy · Coastal FloodNew Castle County · forecast zone New Castle One storm episode: 4 records in 3 places; the totals are the episode's.	0	0	$5.8M
2021-09-01	Hurricane Ida · Flash FloodCoochs Bridge, New Castle County	0	0	$3.9M
1996-01-07	Coastal FloodSussex County · forecast zone Delaware Beaches One storm episode: 2 records; the totals are the episode's.	0	0	$3.8M
1998-02-04	Coastal FloodSussex County · forecast zone Delaware Beaches One storm episode: 2 records; the totals are the episode's.	0	5	$3.1M
1998-01-28	Coastal FloodSussex County · forecast zone Delaware Beaches One storm episode: 2 records; the totals are the episode's.	0	0	$2.4M

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 Delaware?

Delaware'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.

Floods: Delaware and the United States by decade (2020s to June 30, 2026)
Decade	Delaware	United States	Delaware's share
1996-99	63	20,986	0.30%
2000s	188	54,913	0.34%
2010s	242	68,322	0.35%
2020-26	122	43,563	0.28%

Source: NOAA NCEI Storm Events Database.

The most recent floods and flash floods in Delaware

The 12 most recent records, to June 30, 2026
Date	Record	Damage
2026-06-14	Flash FloodGlasgow, New Castle County	$5K
2026-02-23	Coastal FloodSussex County · forecast zone Inland Sussex	–
2026-02-23	Coastal FloodSussex County · forecast zone Delaware Beaches	–
2025-10-29	Coastal FloodSussex County · forecast zone Inland Sussex	–
2025-10-29	Coastal FloodSussex County · forecast zone Delaware Beaches	–
2025-10-12	Coastal FloodKent County · forecast zone Kent	–
2025-10-12	Coastal FloodSussex County · forecast zone Inland Sussex	–
2025-10-12	Coastal FloodSussex County · forecast zone Delaware Beaches	–
2025-10-01	Coastal FloodSussex County · forecast zone Inland Sussex	–
2025-10-01	Coastal FloodSussex County · forecast zone Delaware Beaches	–
2025-08-21	Coastal FloodKent County · forecast zone Kent	–
2025-08-21	Coastal FloodSussex County · forecast zone Inland Sussex	–

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 Delaware

FEMA has declared 7 disasters in Delaware 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); 7 were major disasters, the latest on July 5, 2006.

The 12 most recent
Declared	Number	Title	Areas named
2006-07-05	DR-1654	Severe Storms and Flooding	1
2004-11-15	DR-1572	Severe Storms, Tornadoes, and Flooding From the Remnants of	1
1998-02-13	DR-1205	Severe Winter Storms, High Winds, and Flooding	1
1994-03-16	DR-1017	Severe Ice Storms and Flooding	2
1993-01-15	DR-976	Severe Coastal Storm & Flooding	1
1992-02-06	DR-933	Severe Coastal Storm	2
1962-03-09	DR-126	Severe Storms, High Tides & Flooding	1

Source: FEMA OpenFEMA Disaster Declarations Summaries (v2), through October 2, 2026. OpenFEMA dataset page.