The National Weather Service issued Tornado Watch #605 at 3:00 p.m. EDT on Thursday, Aug. 20, covering Southern Maryland, New Castle County, and 15 other counties across four states. The watch expires at 10:00 p.m. EDT.
A separate tornado warning was issued for Northeastern Maryland while the watch remained active. Residents were urged to seek shelter immediately.
Watch vs. Warning: The Operational Difference
A tornado watch means atmospheric conditions are favorable for tornado formation. Be ready to act.
A tornado warning means a tornado has been spotted or indicated on radar. Take shelter now.
The watch is a heads-up. The warning is the sirens.
The NWS issued the watch for Southern Maryland and Delaware’s New Castle County at 3:00 p.m. The warning for Northeastern Maryland came later, with zero notice for preparation.
Practical rule: Know your county name and your local siren sound before storms arrive.
The 10 P.M. Deadline: Why It Exists
NWS watches carry expiration times because forecast conditions change. This one runs six hours—3:00 p.m. to 10:00 p.m.
The evening window matters. Daytime heating peaks in late afternoon, and tornado risk typically rises into the evening hours across the Mid-Atlantic.
For Maryland and Delaware residents, the deadline means having a plan ready before dinner. Not after dark.
Before 10 p.m.:
– Charge your phone
– Prepare a go-kit
– Identify your safe room
– Enable wireless emergency alerts
Affected Counties: The Full Scope
| State | Counties Under Watch |
|---|---|
| Delaware | Kent, New Castle, Sussex |
| Maryland | Caroline, Kent, Queen Anne’s, Talbot |
| Pennsylvania | Bucks, Chester, Delaware, Montgomery, Philadelphia |
| New Jersey | Atlantic, Burlington, Camden, Cape May, Cumberland, Gloucester, Salem |
A single watch can span multiple states. Do not assume safety because you sit at the watch’s edge. The NWS Mount Holly office issued the watch at 3:00 p.m. with broad regional coverage.
When a Watch Becomes a Warning: Northeastern Maryland
The Northeastern Maryland warning came while the watch was still active. Residents were told to move to basements or interior rooms on the lowest floor.
Stay away from windows. Cover your head. Do not attempt to outrun a tornado in a vehicle.
Warnings can arrive with minutes of lead time—or none. The watch window is your only guaranteed preparation period.
Five Steps Before 10 P.M.
- Monitor local radar and NOAA Weather Radio.
- Prepare your safe room—basement, storm cellar, or interior bathroom.
- Assemble an emergency kit: water, flashlight, batteries, first aid, important documents.
- Secure outdoor furniture and loose objects that could become projectiles.
- Set a phone alarm for 9:30 p.m. to re-check watch status.
If the watch expires, storms can still develop. Stay vigilant through the night.
Myths That Put You at Risk
Myth 1: “A watch means a tornado is already on the ground.” False. It means conditions are favorable.
Myth 2: “I live in a valley, so I’m safe.” Tornadoes cross valleys and rivers.
Myth 3: “Opening windows equalizes pressure.” Dangerous and ineffective. Keep windows closed.
Myth 4: “Only mobile homes are at risk.” Permanent homes are destroyed by tornadoes regularly.
The Maryland and Delaware coastal plain is flat. Tornadoes have occurred there. Geography does not grant immunity.
After the Watch Expires
If severe weather persists past 10 p.m., the NWS may issue a new watch or warnings. Stay tuned to local news and official channels, including @NWSMountHolly on social media.
Watches can be re-issued. If a warning follows the watch’s expiration, treat it with identical urgency.
The 10 p.m. deadline is not a safety guarantee. It is a benchmark for re-evaluating your readiness.
💡 Frequently Asked Questions (FAQ)
- Q: What is the difference between a tornado watch and a tornado warning?
- A: A tornado watch means conditions are favorable for tornado formation; be ready to act. A tornado warning means a tornado has been spotted or indicated on radar; take shelter immediately.
- Q: Why does the tornado watch expire at 10 p.m. EDT?
- A: NWS watches carry expiration times because forecast conditions change. This watch runs from 3 p.m. to 10 p.m. EDT, covering the peak tornado risk period in the evening for the Mid-Atlantic.
- Q: What should I do before the 10 p.m. deadline?
- A: Charge your phone, prepare a go-kit, identify your safe room, and enable wireless emergency alerts. Have a plan ready before dinner, not after dark.
Extended Reading
The NWS Mount Holly statement at 3:00 p.m. confirmed Tornado Watch #605’s scope and expiration. The Delaware Online report published Aug. 20, 2026, listed all affected counties and the exact 3:00 p.m. issuance time. The BayNet’s coverage focused on Southern Maryland’s inclusion under the watch through 10 p.m.
Before the clock strikes 10, have a plan. When a warning hits, there is no time to think.