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Natural Hazards

Many types of severe weather affect Delaware. Learn how to prepare for our state’s most common natural hazard threats:

  • Flooding

    Flooding is the most common natural disaster we face. All floods are different: some develop slowly during extended rain when a warming trend follows a heavy snow, while others, such as flash floods, can occur quickly without visible signs of rain.

    Prepare for flooding no matter where you are, but particularly if you are in a low-lying area, near water or downstream from a dam. Find important information on flooding at NOAA’s Flood safety website (link opens in new tab).

    Flood Severity Terms

    Flood Watch: Flooding is possible. Tune in to NOAA Weather Radio, commercial radio, or television for information.

    Flash Flood Watch: Flash flooding is possible. Be prepared to move to higher ground; listen to NOAA Weather Radio, commercial radio, or television for information.

    Flood Warning: Flooding is occurring or will occur soon; if advised to evacuate, do so immediately.

    Flash Flood Warning: A flash flood is occurring; seek higher ground on foot immediately.

    Prepare Your Home

    • Research and purchase flood insurance. Homeowners’ insurance does not cover flooding. Note that many flood insurance policies take at least 30 days to go into effect.
    • Elevate the furnace, water heater, and electric panel in your home if you live in an area that has a high flood risk.
    • Consider installing “check valves” to prevent flood water from backing up into the drains of your home.
    • If feasible, construct barriers to stop floodwater from entering the building and seal walls in basements with waterproofing compounds.

    Stay Safe Around Flooding

    • If water has entered a garage or basement, do not walk through it. It may contain hazardous materials.
    • Do not try to drive over a flooded road. If your car stalls, abandon it immediately. Attempting to move a stalled vehicle in flood conditions can be fatal.
    • Do not walk through moving water. Six inches of moving water can make you fall. If you must walk in water, walk where the water is not moving. Use a stick to check the firmness of the ground in front of you.
    • Stay clear of water that is in contact with downed power lines.
    • Do not allow children to play around high water, storm drains, or any flooded areas.
    • If you are asked to leave your property, disconnect all electrical appliances and shut off electric circuits. If advised by your local utility, shut off gas service, as well.

    Plan for Evacuation

    • If you feel that you will be in danger, evacuate!
    • If you have pets or farm animals, take them with you or make appropriate arrangements for them to stay far away from potential flood danger.
    • Visit our Evacuation Information page.
  • Hurricanes

    Even without a direct hit, hurricanes can cause storm surge and severe coastal flooding, high winds, inland flooding, tornadoes and large waves and rip currents.

    Use the NOAA National Hurricane Center website opens in a new tab for current tropical storm and hurricane conditions and the NWS Hurricane Preparedness (link opens in new tab) page to stay up to date and for more information.

    Hurricane Severity Terms

    Tropical storm: Maximum sustained surface wind speed using a one-minute average of 39 to 73 mph.

    Hurricane (also known as a typhoon or a cyclone): Maximum sustained surface wind speed using a one-minute average of more than 74 mph.

    Tropical Storm or Hurricane Watch: Sustained winds of the relevant category or higher are possible within the specific area. Usually issued 48 hours in advance of the area being hit by the storm force winds.

    Tropical Storm or Hurricane Warning: Sustained winds of the relevant category or higher are expected shortly to affect the specific area. Usually issued 36 hours in advance of the area being hit by the storm force winds.

    Hurricane Severity Categories: Severity of hurricanes is rated according to the Saffir-Simpson Hurricane Scale.

    Category 1: 74 to 95 mph with dangerous winds that will cause some damage.

    Category 2: 96 to 110 mph with dangerous winds that will cause extensive damage including major roof and siding damage.

    Category 3: 111 to 129 mph with dangerous winds that will cause devastating damage including removal of roof and decks. Electricity and water unavailable for several days to weeks.

    Category 4: 130 to 156 mph with dangerous winds that will cause catastrophic damage including most of roof structure and some exterior walls, uprooted trees, downed power lines, and power outages that can last weeks or months.

    Category 5: 157 mph or higher with dangerous winds that will cause catastrophic damage including total destruction of built structures, total roof failure, and wall collapses. The area will be uninhabitable for weeks or months.

    Graphic displaying hurricane categories on the Saffir-Simpson Scale

    Prepare Your Home

    • Know your hurricane and storm surge risk.
    • Make an emergency plan, talk about it with your family and friends, and practice it.
    • Gather supplies in your emergency kits.
    • Know your evacuation zone and different evacuation routes (link opens in new tab) to take to go inland or off the peninsula. Remember: Delaware is surrounded on 3 sides by water, so you may not be able to go West / inland. Also, there may be many bridges along your route, and they will close if there are sustained winds at or above 45 mph. Don’t get stuck because you forgot about a low-lying area or a bridge!
    • Strengthen your home by cleaning gutters, bringing in outside furniture, keeping shrubs and other landscaping clean, and considering hurricane shutters.
    • Get tech ready by keeping your cell phone charged and having a charged power bank.
    • Take photographs of your home (inside and outside) in case anything gets damaged during the hurricane and flooding.
    • Consider getting flood insurance (link opens in new tab). Even if you do not live near the water, you can still be flooded because of drainage ditches, low-lying areas, high tides, storm surge, and others.
    • Check in with and help your neighbors, especially those who do not have family near by, are seniors, or may need additional help making a plan and staying safe.
    • Remember to take extra care planning if you, anyone in your home, or family nearby is someone with functional, access, or medical needs, including pets and service animals. They will need more support and more time to get ready.
    • If you have a business, make sure you have a continuity of operations plan in case you need to reduce the services, hours, staff, or close completely. Or your business may have greater demands because of the services and products you provide. Plan for either a decrease or an increase of demands.

    Plan for Evacuation

    • Visit our Evacuation Information page.
    • Think about what you need to do differently with COVID-19. Read about the latest in Delaware and ways to prepare with COVID-19 in mind on the Delaware COVID-19 website (link opens in new tab).
    • Plan far ahead of time where you will go and how you will get there. If you are planning to stay with family or friends, make sure they know. If you have pets, make sure your destination is pet-friendly (and if it is not, make other plans!).
    • Identify several places you could go, and choose places in different directions so you have options in case some of them are not available or accessible.
    • Have several alternate routes (link opens in new tab) out of your neighborhood and the area. If you plan to use public transportation, especially if you use ParaTransit (link opens in new tab), make sure you know their policies and if they will change service during a disaster.
    • Monitor local radio and television news outlets or listen to NOAA Weather Radio for the latest developments.
    • Start preparing and packing days in advance, even if it’s sunny and beautiful weather, so if local authorities advise you to evacuate, you can leave as quickly as possible.
    • Have a plan for if you are out of town or at work, but your pets, backyard livestock, or other animals are back at home.
    • Your plan of LAST RESORT should be going to a community shelter. The community shelters in Delaware are safe, but you will be much more comfortable staying with family or friends outside the area.
  • Winter Storms

    The National Weather Service refers to winter storms as “Deceptive Killers” with deaths indirectly caused by the storms. Icy roads cause traffic deaths while prolonged exposure can result in death due to hyperthermia. Prepare for winter weather before it strikes — and don’t forget your pets and farm animals.

    Visit the National Weather Service (NWS) Mount Holly website (link opens in new tab), Facebook (link opens in new tab), and Twitter (link opens in new tab).

    Winter Storm Severity Terms

    Freezing rain: Creates a coating of ice on roads and walkways.

    Sleet: Rain turns to ice pellets before reaching the ground. Sleet also causes roads to freeze and become slippery.

    Winter Weather Advisory: Cold, ice, and snow are expected.

    Frost/Freeze Warning: Below freezing temperatures are expected.

    Winter Storm Watch: Severe weather such as heavy snow or ice is possible in the next day or two.

    Winter Storm Warning: severe winter conditions have begun or will begin soon.

    Blizzard Warning: Heavy snow and strong winds will produce a blinding snow, near zero visibility, deep drifts, and life-threatening wind chill.

    Prepare Your Home and Vehicle

    • Add the following supplies to your disaster kit in preparation for winter weather:
      • Rock salt to melt ice on walkways or sand to improve traction
      • Snow shovels and other snow removal equipment
      • Adequate clothing and blankets to keep you warm
    • Hire a contractor to check the structural stability of the roof to sustain unusually heavy weight from the accumulation of snow or water if drains on flat roofs do not work.
    • If you have a car, fill the gas tank in case you have to leave. In addition, check or have a mechanic check the following items on your car:
      • Antifreeze levels – ensure they are sufficient to avoid freezing.
      • Battery and ignition system – should be in top condition and battery terminals should be clean.
      • Brakes – check for wear and fluid levels.
      • Exhaust system – check for leaks and crimped pipes and repair or replace as necessary. Carbon monoxide is deadly and usually gives no warning.
      • Fuel and air filters – replace and keep water out of the system by using additives and maintaining a full tank of gas.
      • Heater and defroster – ensure they work properly.
      • Lights and flashing hazard lights – check for serviceability.
      • Oil – check for level and weight. Heavier oils congeal more at low temperatures and do not lubricate as well.
      • Thermostat – ensure it works properly.
      • Tires – make sure the tires have adequate tread. All-weather radials are usually adequate for most winter conditions. However, some jurisdictions require that to drive on their roads, vehicles must be equipped with chains or snow tires with studs.
      • Windshield wiper equipment – repair any problems and maintain proper washer fluid level.
  • Tornadoes

    Tornadoes are nature’s most violent storms. Planning and practicing specifically how and where you take shelter could save your life. Be prepared to act quickly.

    Tornado Severity Terms

    Tornado Watch: Prepare yourself! A tornado is possible in or near the watch area. Watch areas are identified by county.

    Tornado Warning: Take Action! A tornado has been sighted in your area. Warnings are also identified by city area or region of a county.

    Prepare Your Home

    • Some important tips for preparing yourself and your homes for tornadoes can be found at the NOAA website (link opens in new tab).
    • Find out what kinds of warning and alert systems your community uses: sirens, media, or smart phones.