National Weather ServiceDelawareFlash Flood WarningArchive to October 1, 2026
Flash Flood Warnings in Delaware
The National Weather Service issued 23 flash flood warnings for Delaware in 2025 and 12 a year on average in 2008-2025; in 2021-2025 it had the 46th most of any state. 2026 through September: 21, 81% above the average of 12 for those months in 2008-2025. New Castle was covered most often (142 times since 2008).
How many flash flood warnings does Delaware get?
Every flash flood warning that covered part of Delaware. 2026 is an outline: the year is not over.
The numbers
| Year | Count |
|---|---|
| 2026 (through September) | 21 |
| 2025 | 23 |
| 2024 | 12 |
| 2023 | 17 |
| 2022 | 1 |
| 2021 | 12 |
| 2020 | 15 |
| 2019 | 10 |
| 2018 | 28 |
| 2017 | 12 |
| 2016 | 6 |
| 2015 | 8 |
| 2014 | 8 |
| 2013 | 17 |
| 2012 | 9 |
| 2011 | 13 |
| 2010 | 5 |
| 2009 | 9 |
| 2008 | 7 |
Source: Iowa Environmental Mesonet archive of National Weather Service watches, warnings and advisories (VTEC); National Weather Service. Data as of October 1, 2026.
When in the year does Delaware get them?
Sum of 2008-2025; the busiest month is labelled.
Source: Iowa Environmental Mesonet archive of National Weather Service watches, warnings and advisories (VTEC); National Weather Service. Data as of October 1, 2026.
Where in Delaware?
| County or forecast zone | Since 2008 | Since 2023 | Last issued |
|---|---|---|---|
| New Castle | 142 | 51 | September 3, 2026 |
| Sussex | 80 | 19 | August 28, 2026 |
| Kent | 67 | 11 | August 20, 2026 |
The NWS issues these products for counties or forecast zones; a zone can be part of a county or a mountain range.
Source: Iowa Environmental Mesonet archive of National Weather Service watches, warnings and advisories (VTEC); National Weather Service. Data as of October 1, 2026.
The latest flash flood warnings for Delaware in AreaZine's record
NWS Mount HollyWarningSeptember 3, 2026
Flash Flood Warning: New Castle, Burlington, Camden and 6 more, DE and NJ
Expired 5:30 a.m. EDT, September 3, 2026
NWS Mount HollyWarningSeptember 1, 2026
Flash Flood Warning: New Castle, Gloucester, Salem and 2 more, DE and NJ
Expired 12:45 a.m. EDT, September 2, 2026
NWS Mount HollyWarningAugust 28, 2026
Flash Flood Warning: Sussex, DE
Expired 5:15 p.m. EDT, August 28, 2026
NWS Mount HollyWarningAugust 27, 2026
Flash Flood Warning: New Castle and Salem, DE and NJ
Expired 5:45 p.m. EDT, August 27, 2026
NWS Mount HollyWarningAugust 27, 2026
Flash Flood Warning: New Castle, Gloucester and Delaware County, DE and NJ
Expired 2:30 p.m. EDT, August 27, 2026
NWS Mount HollyWarningAugust 23, 2026
Flash Flood Warning: New Castle and Delaware County, DE and PA
Expired 7:45 a.m. EDT, August 23, 2026
NWS Mount HollyWarningAugust 20, 2026
Flash Flood Warning: Kent, Caroline and Queen Anne's, DE and MD
Expired 11:00 p.m. EDT, August 20, 2026
NWS Mount HollyWarningAugust 20, 2026
Flash Flood Warning: New Castle, Camden, Gloucester and 5 more, DE and NJ
Expired 9:45 p.m. EDT, August 20, 2026
This list is AreaZine's record of the NWS alert feed, kept since April 6, 2026; the counts above come from the complete IEM archive.
Source: National Weather Service alerts (api.weather.gov).
What is a flash flood warning?
A flash flood warning means flash flooding is happening or about to happen: water rising fast in streams, streets or dry washes, usually within six hours of heavy rain or a dam or levee failure. A warning means the hazard is happening, about to happen, or very likely: act now to protect people and property. The national record · Every warning type in Delaware.