Alert archive / Maryland / Flash Flood Warnings
Flash Flood Warnings in Maryland, 2025
67 flash flood warnings in 2025. An alert counts here when it covered any part of the state, so the counties below add up to more than the state. The archive of flash flood warnings reaches back to 1986.
Flash Flood Warnings by county
Each county as a circle sized by its count in 2025. Tap one for its archive.
- Flash Flood Warnings
- 67
- Busiest month
- July43 flash flood warnings
- Busiest day
- July 31, 202510 flash flood warnings
Over time
By month
Warning verification
How often warnings here had a storm report inside them, and how much warning the reports had.
45 of 67 flash flood warnings covering Maryland in 2025 had a flash flood report inside them; 99 of 108 flash flood reports fell inside a warning, on average 58 minutes after it went out.
Maryland, 2025
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Flash flood warnings | 67 | 45 | 33% | 108 | 92% | 58 min |
Each office's whole area, 2025
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS Baltimore/Washington: flash flood warnings | 143 | 91 | 36% | 251 | 93% | 66 min |
| NWS Philadelphia/Mount Holly: flash flood warnings | 96 | 55 | 43% | 203 | 96% | 67 min |
| NWS Wakefield, VA: flash flood warnings | 173 | 131 | 24% | 324 | 92% | 84 min |
An office's figures cover every county it serves, including across state lines.
Verified by the Iowa Environmental Mesonet's Cow, which matches each storm-based warning with the local storm reports inside its polygon while it was in force, within 15 km of its edge: a tornado warning counts as verified on a tornado report, a severe thunderstorm warning on hail of 1 inch or more, a gust of 58 mph or more, or wind damage, a flash flood warning on a flash flood report. The false alarm ratio is the share of warnings with no such report; "inside a warning" is the probability of detection, the share of reports that fell inside one; lead time runs from the warning's issue to each report inside it, counting zero for a report that came first. A warning with no report is not proof nothing happened: reports come from spotters, the public and damage surveys, and are thin where few people live.
The alerts
Every alert, in the order issued. Times are local, Eastern Time. Each opens its own page with the text, the map, the radar and the sounding.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Mar 16, 11:59 PM EDT | Flash Flood Warning | AKQ | Wicomico | 3 hr |
| May 5, 7:38 PM EDT | Flash Flood Warning | LWX | Frederick | 3 hr |
| May 13, 12:57 PM EDT | Flash Flood Warning | LWX | Allegany, Garrett | 5 hr |
| May 13, 1:00 PM EDT | Flash Flood Warning | LWX | Allegany, Garrett | 5 hr |
| May 13, 1:52 PM EDT | Flash Flood Warning | LWX | Garrett | 4 hr |
| May 13, 2:49 PM EDT | Flash Flood Warning | LWX | Allegany | 3 hr |
| May 30, 7:54 PM EDT | Flash Flood Warning | LWX | Howard, Montgomery, Prince George's | 3 hr |
| May 30, 8:14 PM EDT | Flash Flood Warning | LWX | Anne Arundel, Baltimore, Howard, City of Baltimore | 3 hr |
| Jun 6, 4:47 PM EDT | Flash Flood Warning | LWX | Allegany | 2 hr |
| Jun 13, 8:11 PM EDT | Flash Flood Warning | LWX | Montgomery, Prince George's | 3 hr |
| Jun 13, 9:47 PM EDT | Flash Flood Warning | LWX | Anne Arundel | 3 hr |
| Jun 15, 7:01 PM EDT | Flash Flood Warning | LWX | Charles | 3 hr |
| Jun 15, 7:05 PM EDT | Flash Flood Warning | LWX | Charles, Prince George's | 3 hr |
| Jun 18, 1:25 PM EDT | Flash Flood Warning | LWX | Montgomery | 63 min |
| Jun 18, 6:30 PM EDT | Flash Flood Warning | LWX | Montgomery | 108 min |
| Jun 30, 5:07 PM EDT | Flash Flood Warning | LWX | Baltimore, Harford | 2 hr |
| Jun 30, 7:37 PM EDT | Flash Flood Warning | LWX | Baltimore, Harford | 113 min |
| Jun 30, 8:39 PM EDT | Flash Flood Warning | LWX | Harford | 52 min |
| Jul 1, 2:54 PM EDT | Flash Flood Warning | LWX | Montgomery | 2 hr |
| Jul 1, 4:31 PM EDT | Flash Flood Warning | LWX | Anne Arundel, Baltimore, City of Baltimore | 3 hr |
| Jul 7, 12:51 PM EDT | Flash Flood Warning | AKQ | Dorchester | 2 hr |
| Jul 7, 1:04 PM EDT | Flash Flood Warning | PHI | Talbot | 2 hr |
| Jul 8, 5:30 PM EDT | Flash Flood Warning | LWX | Harford | 2 hr |
| Jul 8, 5:38 PM EDT | Flash Flood Warning | LWX | Cecil | 2 hr |
| Jul 9, 5:44 PM EDT | Flash Flood Warning | LWX | Montgomery | 3 hr |
| Jul 9, 6:06 PM EDT | Flash Flood Warning | LWX | Carroll, Howard | 2 hr |
| Jul 9, 7:10 PM EDT | Flash Flood Warning | LWX | Anne Arundel, Montgomery, Prince George's | 69 min |
| Jul 9, 7:21 PM EDT | Flash Flood Warning | LWX | Baltimore, Carroll, Harford | 3 hr |
| Jul 9, 9:41 PM EDT | Flash Flood Warning | AKQ | Somerset | 3 hr |
| Jul 12, 4:49 PM EDT | Flash Flood Warning | LWX | Montgomery | 3 hr |
| Jul 12, 6:18 PM EDT | Flash Flood Warning | LWX | Frederick | 77 min |
| Jul 13, 1:08 PM EDT | Flash Flood Warning | LWX | Prince George's | 118 min |
| Jul 13, 1:11 PM EDT | Flash Flood Warning | LWX | Baltimore, Howard, City of Baltimore | 2 hr |
| Jul 14, 2:48 PM EDT | Flash Flood Warning | LWX | Washington | 3 hr |
| Jul 14, 5:45 PM EDT | Flash Flood Warning | LWX | Montgomery | 3 hr |
| Jul 14, 6:05 PM EDT | Flash Flood Warning | LWX | Montgomery, Prince George's | 2 hr |
| Jul 14, 6:13 PM EDT | Flash Flood Warning | LWX | Anne Arundel, Baltimore, Howard, City of Baltimore | 3 hr |
| Jul 14, 6:34 PM EDT | Flash Flood Warning | LWX | Anne Arundel, Howard, Prince George's | 2 hr |
| Jul 15, 12:27 AM EDT | Flash Flood Warning | AKQ | Somerset | 3 hr |
| Jul 16, 9:54 PM EDT | Flash Flood Warning | LWX | Cecil | 3 hr |
| Jul 16, 10:14 PM EDT | Flash Flood Warning | LWX | Harford | 3 hr |
| Jul 19, 3:33 PM EDT | Flash Flood Warning | AKQ | Worcester | 109 min |
| Jul 19, 3:49 PM EDT | Flash Flood Warning | AKQ | Worcester | 2 hr |
| Jul 19, 5:03 PM EDT | Flash Flood Warning | LWX | Montgomery, Prince George's | 3 hr |
| Jul 19, 5:24 PM EDT | Flash Flood Warning | LWX | Montgomery, Prince George's | 3 hr |
| Jul 19, 5:52 PM EDT | Flash Flood Warning | LWX | Prince George's | 3 hr |
| Jul 19, 5:54 PM EDT | Flash Flood Warning | LWX | Montgomery | 113 min |
| Jul 19, 6:15 PM EDT | Flash Flood Warning | LWX | Anne Arundel, Montgomery, Prince George's | 115 min |
| Jul 19, 6:22 PM EDT | Flash Flood Warning | LWX | Montgomery | 107 min |
| Jul 19, 9:13 PM EDT | Flash Flood Warning | AKQ | Dorchester, Wicomico | 3 hr |
| Jul 31, 1:05 PM EDT | Flash Flood Warning | LWX | Baltimore, Harford | 3 hr |
| Jul 31, 2:27 PM EDT | Flash Flood Warning | LWX | Prince George's | 84 min |
| Jul 31, 2:49 PM EDT | Flash Flood Warning | LWX | Anne Arundel | 94 min |
| Jul 31, 3:03 PM EDT | Flash Flood Warning | LWX | Baltimore | 39 min |
| Jul 31, 3:17 PM EDT | Flash Flood Warning | LWX | Baltimore, Cecil, Harford | 3 hr |
| Jul 31, 3:33 PM EDT | Flash Flood Warning | LWX | Montgomery | 3 hr |
| Jul 31, 4:00 PM EDT | Flash Flood Warning | LWX | Baltimore | 3 hr |
| Jul 31, 4:08 PM EDT | Flash Flood Warning | LWX | Montgomery | 2 hr |
| Jul 31, 4:23 PM EDT | Flash Flood Warning | LWX | Baltimore, Harford | 3 hr |
| Jul 31, 4:27 PM EDT | Flash Flood Warning | LWX | Baltimore, Carroll, Frederick, Howard, Montgomery, City of Baltimore | 3 hr |
| Aug 13, 5:47 PM EDT | Flash Flood Warning | LWX | Anne Arundel, Baltimore, City of Baltimore | 2 hr |
| Aug 13, 6:20 PM EDT | Flash Flood Warning | LWX | Baltimore, Harford | 88 min |
| Aug 13, 6:49 PM EDT | Flash Flood Warning | LWX | Baltimore, Harford | 2 hr |
| Aug 14, 4:10 PM EDT | Flash Flood Warning | LWX | Anne Arundel, City of Baltimore | 59 min |
| Aug 14, 4:14 PM EDT | Flash Flood Warning | LWX | Baltimore, City of Baltimore | 2 hr |
| Aug 14, 6:59 PM EDT | Flash Flood Warning | AKQ | Wicomico, Worcester | 2 hr |
| Aug 20, 7:00 PM EDT | Flash Flood Warning | PHI | Caroline, Queen Anne's | 2 hr |
By county
Every county with at least one alert. A county page lists each alert that covered it.
- Montgomery County18
- Baltimore County17
- Prince George's County12
- Harford County11
- Anne Arundel County10
- City of Baltimore8
- Howard County7
- Allegany County4
- Wicomico County3
- Frederick County3
- Garrett County3
- Cecil County3
- Carroll County3
- Worcester County3
- Charles County2
- Dorchester County2
- Somerset County2
- Talbot County1
- Washington County1
- Caroline County1
- Queen Anne's County1
The busiest days
Days with the most alerts issued, by UTC date.
Nearby
Alerts in force nowTornadoes on recordThe radar archive20242026
Sources
National Weather Service watches, warnings, advisories and statements from the Iowa Environmental Mesonet's VTEC archive, which reconstructs tornado, severe thunderstorm, flash flood and marine warnings back to 1986 from the NWS text archive. Storm Prediction Center watches and mesoscale discussions from SPC's archive through the Mesonet. County centers from the US Census Bureau. Warning verification from the Mesonet's Cow. Rebuilt daily.