Maryland Flooding: Ocean City, the Chesapeake Bay, and Inland Flash Floods
- Is Maryland Flooding Right Now? Where to Check First
- Three Kinds of Maryland Floods, and Where Each One Hits
- Keeping the Sump Pump and Essentials Running When the Power Fails
- BGE, Pepco, Delmarva Power, and Others: Maryland Electric Companies by Territory
- Check Your Own Address: Flood Maps, Evacuation Zones, and Insurance
- Conclusion
- FAQs
A street in Annapolis can flood under a blue sky. Ocean City can deal with water for days during a nor'easter. In Ellicott City, a dry street can turn dangerous in less than two hours after intense rain. Flooding in Maryland is really three different problems, with very different warning times. This guide shows where to check conditions, what major floods have looked like, who to call when the power goes out, and how to keep a sump pump and other essentials running.
Is Maryland Flooding Right Now? Where to Check First
Flood conditions can change with the tide, rainfall, and river levels, so start with the agencies that issue warnings and run the gauges. Bookmark these pages before the next storm.
What you need | Where to get it | Covers |
Flood and coastal flood warnings, forecasts | NWS Baltimore/Washington (office in Sterling, VA): weather.gov/lwx | Baltimore, Annapolis, Ellicott City, central and western Maryland |
Coastal flood warnings and tide forecasts for the beach | NWS Wakefield, VA: weather.gov/akq | Ocean City, Assateague, and the Lower Eastern Shore |
River and tide gauge levels with flood stages | NOAA National Water Prediction Service: water.noaa.gov (for example, "Atlantic Coast near Ocean City Inlet" and "Patapsco River at Ellicott City") | Statewide |
Tide predictions and high tide flooding outlooks | NOAA Tides and Currents: tidesandcurrents.noaa.gov | Annapolis, Baltimore, Ocean City Inlet, and other tide stations |
Local emergency alerts | Maryland Department of Emergency Management (MDEM): MdReady.Maryland.gov lists each county's alert sign-up | All 24 jurisdictions |
Evacuation zone | MDEM Know Your Zone: knowyourzonemd.com | Coastal counties, Baltimore City, Annapolis, Ocean City |
Power outages | Your electric company's outage map (see the utility table below) | By service territory |
If you don't know which NWS office covers your address, enter your ZIP code at weather.gov. MDEM's MdReady site links to local alert systems, including CodeRED in Worcester County and ReadyHoCo in Howard County. NWS's Turn Around Don't Drown guidance says six inches of fast-moving water can knock an adult over, while 12 inches can carry away most cars. More than half of flood deaths involve vehicles driven into floodwater. If a road is covered, turn around. A flash flood watch gives you time to prepare. A warning means water is expected or already happening, so move to safety. Which warning matters most depends on where you live. Maryland's coast, Bay shoreline, and inland stream valleys flood for different reasons.
Three Kinds of Maryland Floods, and Where Each One Hits
MDEM describes flash flooding, general flooding from steadier rain, and tidal surge as different sources of flooding in Maryland. For most residents, the useful distinction is between coastal water, high tides around the Bay, and fast-moving inland floods.
Flood type | Where | Typical trigger | Warning time | Documented example |
Ocean and coastal bay flooding | Ocean City, Assateague, the coastal bays | Nor'easters, tropical systems, and persistent northeast wind stacking water over several tide cycles | Days (storms are forecast) | Sept 23 to 26, 2026 nor'easter: Ocean City water levels topped 5 feet MLLW for the first time in nearly 14 years (NWS Wakefield) |
Chesapeake Bay tidal ("sunny day") flooding | Annapolis, Baltimore's harbor, Bay and tidal river towns | Above-normal tides, sometimes with no storm at all; storm surge in the worst cases | Hours to days (tide forecasts) | Hurricane Isabel, Sept 19, 2003: storm tide of 8.34 feet at Baltimore and 7.47 feet at Annapolis, NGVD 1929 (NWS) |
Inland flash flooding | Ellicott City and other steep stream valleys | Intense rain over a small watershed | Minutes | July 30, 2016: more than 6 inches of rain, much of it in 90 minutes or less (NWS Baltimore/Washington) |
Ocean City and the coastal bays
Ocean City sits on a flat barrier island, and its town hazard plan says virtually all of the town lies within the 100-year floodplain, with bayside streets flooding regularly. Nor'easters are a major cool-season threat because northeast winds can push water toward the coast over several tide cycles. The Ash Wednesday Storm of March 6 to 8, 1962 lasted through more than five high tides and affected virtually every building in Ocean City, helping drive later beach, dune, and seawall work. Recent storms show the risk continues: October 2025 brought a 59 mph gust and tides 2 to 3 feet above astronomical levels, while the September 2026 nor'easter produced mainly tidal flooding with 45 to 48 mph gusts. NOAA recorded eight high tide flood days at Ocean City Inlet from May 2025 through April 2026, tying the station's 2009 record.
Annapolis and Baltimore: flooding on a sunny day
High tide flooding doesn't require a hurricane or nor'easter. NOAA defines it as above-normal tides covering normally dry areas, which can put water on streets around the Chesapeake Bay even under clear skies. The Mid-Atlantic recorded a median of nine high tide flood days from May 2025 through April 2026, and NOAA forecasts 15 to 20 days for May 2026 through April 2027. Baltimore recorded a record 12 days in the 2023 to 2024 year. During Hurricane Isabel in 2003, NWS recorded storm tides of 8.34 feet at Baltimore and 7.47 feet at Annapolis. Maryland DNR's Coastal Flood Explorer lets residents check predicted, historic, and current flood depths by address.
Ellicott City and inland Maryland
Inland flooding can develop much faster. On July 30, 2016, more than 6 inches of rain fell around Ellicott City, much of it in roughly 90 minutes, and the Patapsco River rose more than 13 feet in 100 minutes, killing two people. Another major flood on May 27, 2018 brought six to 12 inches in the heaviest band, killed one person, and generated about 1,100 calls to Howard County 911. USGS measured 6.60 inches in three hours in 2016 and 6.56 inches in 2018. Maryland DNR still considers flash flooding one of the state's most dangerous hazards because warnings can provide only minutes to react. Even homes far from the Bay can face serious flooding near a creek, at the bottom of a steep street, or in another low spot.
Keeping the Sump Pump and Essentials Running When the Power Fails
Flash flooding can leave very little time to react, especially when water is rising near a home. If the power goes out at the same time, a sump pump may stop just when you need it most. A portable power station can keep a sump pump and other essentials running from a dry location without producing exhaust.
Keep electrical equipment away from floodwater
Never use an electrical appliance or tool while standing in water. If floodwater reaches an outlet or electrical panel, have an electrician inspect the system before power is restored. CDC guidance also says never to run a gasoline engine inside a home, basement, or garage, or within 20 feet of a door, window, or vent. Keep a power station and its cords on a dry, raised surface. A flooded basement isn't a safe place for either the battery or its connections.
Check your sump pump's power needs
Sump pumps don't all use the same amount of power. For example, Zoeller's 3/10-horsepower Model M53 is rated at 115 volts and 9.7 amps. That's roughly 1,100 volt-amps at its rated load, although actual watts can be lower. Check your own pump's nameplate or manual before choosing backup power. Pump motors can also draw more power briefly when they start.
How long can an EcoFlow DELTA 3 Max run a sump pump?
For a simple planning estimate, use 2,048Wh × 0.85 ÷ load in watts. The 0.85 is a planning assumption for conversion losses, not an EcoFlow specification.
Load | Estimated runtime | Calculation |
Sump pump running nonstop at about 1,100 W | About 1.6 hours of continuous pumping | 2,048 × 0.85 ÷ 1,116 = 1.56 |
Same pump running 1 minute out of every 6 | About 9 hours of coverage | 1.56 hours of pump time ÷ (1/6) = 9.4 |
100 W of small essentials (check device labels) | About 17 hours | 2,048 × 0.85 ÷ 100 = 17.4 |
These are planning examples, not guaranteed runtimes. A sump pump may run almost continuously during a fast-rising flood, which can drain a portable battery much faster. The cycling example also depends entirely on how often your own pump runs. The EcoFlow DELTA 3 Max has 2,400W of output and 4,800W of surge capacity, but that doesn't mean it will start every sump pump. Compare the pump's startup and running requirements with the EcoFlow DELTA 3 Max specifications before connecting it. If the outage continues, recharging matters too. EcoFlow says the EcoFlow DELTA 3 Max can reach 0 to 80% charge in about 68 minutes with wall or generator charging.
For automatic backup
The EcoFlow DELTA Pro Ultra X is the installed option for homeowners who want selected circuits to switch to backup power automatically as part of a whole-home backup setup. Whole-home backup requires Smart Home Panel 3 installed by a licensed electrician, and the amount of the home it can support depends on its electrical loads. For a flood-prone property, discuss equipment placement with the electrician so the system is positioned above the expected flood level where appropriate. Before choosing a battery, check how many watts a sump pump uses at startup and while running. Those numbers tell you what your backup system needs to handle.
If you don't need an installed backup system, a portable option can cover the essentials instead. The EcoFlow DELTA 3 Max is easier to move and can power a sump pump or other individual devices when you need backup without wiring the whole house.
How the two divide the job
The EcoFlow DELTA 3 Max is the portable choice for a sump pump, phones, and a few other essentials during a storm tide or flash flood. It's also a practical fit for renters and Ocean City condo owners who can't make changes to the home's wiring. The EcoFlow DELTA Pro Ultra X is the installed option for homeowners who want selected circuits backed up automatically through Smart Home Panel 3, with installation by a licensed electrician. Batteries cover the gap between the lights going out and the crews arriving. In Maryland, which utility comes to restore power depends on where you live.
BGE, Pepco, Delmarva Power, and Others: Maryland Electric Companies by Territory
Maryland has several investor-owned utilities, cooperatives, and municipal systems. The company that delivers electricity to your home handles the outage, regardless of who supplies your electricity. Check your bill now and save the outage number before a storm.
Electric company (exact name) | Where it serves | Outage map | Outage number and label |
Baltimore Gas and Electric Company (BGE) | Baltimore City; Baltimore and Anne Arundel counties (including Annapolis); most of Howard (including Ellicott City), Carroll, and Harford; parts of Prince George's, Montgomery, and Calvert | "Electric Outages or Downed Wires: 1 (877) 778-2222" (Maryland PSC directory) | |
Potomac Electric Power Company (Pepco) | Most of Montgomery and Prince George's counties | "Emergency/Downed Wires: 1 (877) PEPCO-62 (877-737-2662)" (Maryland PSC directory) | |
Delmarva Power & Light Company (Delmarva Power) | The Upper and Lower Eastern Shore, including the Ocean City area | "Electric Outages or Downed Wires: 1 (800) 898-8042" (Maryland PSC directory; same number in Worcester County Emergency Services' newsletter) | |
The Potomac Edison Company (a FirstEnergy company) | Allegany, Washington, Garrett, and Frederick counties; parts of Carroll, Howard, and Montgomery | "1-888-LIGHTSS (1-888-544-4877)"; or text OUT to 544487 (FirstEnergy's own page) | |
Southern Maryland Electric Cooperative (SMECO) | Calvert, Charles, and St. Mary's counties | "Outage Hotline: (877) 747-6326" (SMECO's own page) | |
Choptank Electric Cooperative | Member-owners in nine Eastern Shore counties: Caroline, Cecil, Dorchester, Kent, Queen Anne's, Somerset, Talbot, Wicomico, and Worcester | "Outage Reporting Number: 1-800-410-4790"; or text OUT to the same number (Choptank's own pages) |
Who serves Ocean City?
Delmarva Power serves most of Ocean City. The town's October 2025 storm update credited Delmarva Power with restoring an outage near 30th Street. Worcester County has more than one electric provider. Choptank Electric serves members in the county, and the Town of Berlin operates its own municipal electric department. If you're on the mainland side, check the company listed on your bill. For a downed line or immediate danger, call 911 first. Stay well away from the line and anything touching it.
Keep food safe during the outage
FoodSafety.gov says an unopened refrigerator keeps food safe for up to four hours. A full freezer can hold food for about 48 hours, while a half-full freezer lasts about 24 hours if the doors stay closed. Food that has touched floodwater should be thrown away. A multi-tide coastal flood can keep crews out for a while, so knowing the food-safety rules before the refrigerator warms up can save you from guessing later.
Check Your Own Address: Flood Maps, Evacuation Zones, and Insurance
Statewide maps are useful, but your own address tells you much more. Four quick checks can show what kind of flood risk you face, where you should go if an evacuation is ordered, and whether you have insurance in place before the next storm.
Check your flood map. Search your address through FEMA's Flood Map Service Center or Maryland's flood map viewer at mdfloodmaps.net.
Find your evacuation zone. MDEM's Know Your Zone uses Zones A, B, and C across 16 counties, Baltimore City, Annapolis, and Ocean City.
Check future tidal flooding. Maryland DNR's Coastal Flood Explorer shows predicted, historic, and current flood depths by address in the coastal zone.
Review flood insurance timing. FloodSmart says a new National Flood Insurance Program policy usually takes effect 30 days after purchase, with limited exceptions. Coverage can reach $250,000 for a home's structure and $100,000 for contents. Renters can buy contents coverage up to $100,000.
That 30-day waiting period matters. Buying a policy after a nor'easter is already in the forecast generally won't protect you from that storm. Before a flood, move valuables to higher levels and keep fuel on hand. Afterward, have electrical systems inspected before using them again. If you live near the Bay, a tidal river, or a creek, look up your flood zone and evacuation zone now. It's much easier to make those decisions before water is moving.
Conclusion
Maryland flooding takes several forms. Ocean City deals with multi-tide coastal flooding from nor'easters and other storms. Annapolis and Baltimore can see high tide flooding on calm days. Inland communities such as Ellicott City can get dangerous flash floods with only minutes of warning. Save the NWS office for your address, sign up for local alerts through MdReady, bookmark your utility's outage map, and check your FEMA flood zone and MDEM evacuation zone. If flooding knocks out the power, an EcoFlow DELTA 3 Max can provide portable backup for a sump pump and essential devices, while homeowners who need automatic backup for selected circuits can discuss the EcoFlow DELTA Pro Ultra X and Smart Home Panel 3 with a licensed electrician.
FAQs
Does Ocean City, Maryland flood?
Yes. Ocean City's hazard plan says virtually all of the town lies within the 100-year floodplain, and bayside and downtown streets can flood during nor'easters and high tides. NOAA recorded eight high tide flood days at Ocean City Inlet from May 2025 to April 2026.
What causes sunny-day flooding in Annapolis and Baltimore?
Sunny-day flooding occurs when above-normal tides push water onto normally dry streets and low-lying areas, even without a storm. NOAA expects 15 to 20 high tide flood days from May 2026 through April 2027, putting some areas around Annapolis, Baltimore, and the Chesapeake Bay at risk.
Why does Ellicott City flood so badly?
Ellicott City sits along the Patapsco River and near steep, narrow stream valleys where heavy rain can move downstream quickly. During the July 2016 flood, more than 6 inches of rain fell in about 90 minutes, and the river rose more than 13 feet in roughly 100 minutes, leaving little time to react.
Can a nor'easter cause flooding in Maryland?
Yes. Strong northeast winds can push water toward the Maryland coast and Chesapeake Bay, especially when they coincide with high tides. During the September 2026 nor'easter, NWS Wakefield reported Ocean City water levels above 5 feet MLLW, with flooding potentially lasting through several tide cycles.
Who do I call if the power goes out in Ocean City?
Delmarva Power serves most of Ocean City, but some nearby mainland addresses use Choptank Electric or the Town of Berlin. For a downed line or immediate danger, call 911 first, stay away, and check your electric bill to confirm your utility.
How do I find my flood zone in Maryland?
Use FEMA's Flood Map Service Center or Maryland's flood map viewer at mdfloodmaps.net to check your property's mapped flood risk. For evacuation information, use MDEM's Know Your Zone map, since flood zones and evacuation zones serve different purposes.
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