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A hurricane is a type of tropical cyclone or severe tropical storm. A typical cyclone is accompanied by thunderstorms, and a counterclockwise circulation of winds near the earth's surface. A hurricane has maximum sustained winds of 74 mph or higher. A tropical storm has sustained winds of 39-73 mph.

photo of hurricane eye

Hurricanes can cause catastrophic damage to coastlines and several hundred miles inland. Hurricanes can produce winds exceeding 155 miles per hour as well as tornadoes and mircrobursts. Moving or airborne debris can break windows and doors and allow high winds and rain inside a home or business. In some hurricanes, wind alone can cause extensive damage such as downed trees and power lines, collapsing weak areas of homes, businesses or other buildings. Additionally, hurricanes can create storm surges along the coast and cause extensive damage from heavy rainfall. Floods and flying debris from the excessive winds are often the deadly and destructive results of these weather events. Slow moving hurricanes traveling into mountainous regions tend to produce especially heavy rain. Excessive rain can trigger landslides or mudslides and flash flooding.

Each hurricane usually lasts for over a week, moving 10-20 miles per hour over the open ocean. Hurricanes gather heat and energy through contact with warm ocean waters. Evaporation from the seawater increases their power. Hurricanes rotate in a counter-clockwise direction around an "eye" in the Northern Hemisphere and clockwise direction in the Southern Hemisphere. The center of the storm or "eye" is the calmest part.

All Atlantic coastal areas, including New Hampshire, are subject to hurricanes or tropical storms. The Atlantic Hurricane Season begins on June 1st and ends on November 30th each year. Historically, the most active time for hurricane development is mid-August through mid-October.

Classification: Hurricanes are classified into five categories according to the Saffir-Simpson Hurricane Wind Scale, based on wind speed and potential to cause damage:

  • Category One – Winds 74-95 mph
    • Very dangerous winds will produce some damage
      • Minor damage to exterior of homes
      • Toppled tree branches, uprooting of smaller trees
      • Extensive damage to power lines, power outages
  • Category Two – Winds 96-110 mph
    • Extremely dangerous winds will cause extensive damage
      • Major damage to exterior of homes
      • Uprooting of small trees and many roads blocked
      • Guaranteed power outages for long periods of time – days to weeks
  • Category Three – Winds 111-129 mph
    • Devastating damage will occur
      • Extensive damage to exterior of homes
      • Many trees uprooted and many roads blocked
      • Extremely limited availability of water and electricity
  • Category Four – Winds 130-156 mph
    • Catastrophic damage will occur
      • Loss of roof structure and/or some exterior walls
      • Most trees uprooted and most power lines down
      • Isolated residential areas due to debris pile up
      • Power outages lasting for weeks to months
  • Category Five – Winds greater than 157 mph
    • Catastrophic damage will occur
      • A high percentage of homes will be destroyed
      • Fallen trees and power lines isolate residential areas
      • Power outages lasting for weeks to months
      • Most areas will be uninhabitable

Familiarize yourself with the terms to the right to help identify hazards associated with hurricanes. Watches and warnings can be issued, not only for hurricanes, but for tropical storms that pose a risk to an area as well.

Take Action Before a Hurricane

Consider taking preventative actions before hurricane season begins and/or before a hurricane arrives. During a hurricane or tropical storm watch (threat of hurricane or tropical storm conditions within 48 hours), monitor local radio or television stations for official emergency information and instructions. You can also find detailed information about hurricane hazards on the National Weather Service National Hurricane Center website and their Twitter and Facebook.

Steps to Be Ready

  1. Complete the Family Emergency Plan pdf file and discuss it as a family. This is a simple way of keeping each member of the family informed on critical information: where to reconnect should you become separated, who to call, and what you will do should an earthquake occur.
  2. Complete the Emergency Contacts Card pdf file and place one in your Emergency Kit.
  3. Prepare an Emergency Kit. The Emergency Kit should be easily accessible should you and your family be forced to shelter in place (stay at home) for a period of time.

Take Action in Your Home

If a hurricane is likely going to impact your area, you should:

  • Listen to the radio or TV for information.
  • Turn off utilities if instructed to do so. Otherwise, turn the refrigerator thermostat to its coldest setting and keep its doors closed.
  • Keep rain gutters and downspouts clear of debris.
  • Close and lock all windows. If possible, cover all of your home's windows. Permanent storm shutters offer the best protection for windows. A second option is to board up windows with 5/8" exterior grade or marine plywood, cut to fit and ready to install. Tape does not prevent windows from breaking.
  • Install straps or additional clips to securely fasten your roof to the frame structure. This will reduce roof damage.
  • Reinforce your garage doors; if wind enters a garage it can cause dangerous and expensive structural damage.
  • If time or circumstance allows, secure first floor doorways with sandbags, duct tape or heavy plastic to protect interior from possible flooding.
  • Install a generator for emergencies.
  • If in a high-rise building, when high winds are present, be prepared to take shelter on a lower floor because wind conditions increase with height.  When flooding may be occurring, be prepared to take shelter on a floor safely above the flooding and wave effects.
  • Learn community hurricane evacuation routes and how to find higher ground. Determine where you would go and how you would get there if you needed to evacuate. If instructed to evacuate, do so following first responder instructions. 
  • Learn the elevation level of your property and whether the land is flood-prone. This will help you know how your property will be affected when storm surge or tidal flooding are forecasted.
  • Ensure you have a supply of water for sanitary purposes such as cleaning and flushing toilets. Fill the bathtub and other large containers with water.
  • Avoid using the phone, except for serious emergencies.
  • Tie down or bring indoors any objects that might be blown around by hurricane winds (outdoor furniture, decorations, garbage cans, display racks, signs and any other loose objects that are normally left outside).
  • If you own a boat, determine how and where to moor and secure it.
  • Ensure that all vehicles are serviced and fueled in case you may need to evacuate. Determine where they can be stored during the storm if you do not evacuate.
  • Be sure trees and shrubs around your home are well trimmed so they are more wind resistant.
  • If you are advised to evacuate, lock the doors when you leave.


Hurricanes cause heavy rains that can cause extensive flood damage in coastal and inland areas. Everyone is at risk and should consider flood insurance protection. Flood insurance is the only way to financially protect your property or business from flood damage. To learn more about your flooding risk and how to protect yourself and your business, visit the Federal Insurance and Mitigation Administration (NFIP) website.

Be Safe During a Hurricane

If you are under a hurricane or tropical storm warning, it means that it is expected to affect your area within 36 hours. It is important to be aware and knowledgeable on what's happening, listen to news reports, secure important items to higher ground and get ready to make the decision on whether you need to evacuate.

If you are advised to evacuate, do so immediately. Evacuation is simple and safer before the hurricane arrives. Don't forget your emergency kit, which should include your Emergency Contacts Card and your Family Emergency Plan which includes your evacuation location options. Have your evacuation plan ready, and follow recommended routes. Know that flash flooding can occur. If there is any possibility of a flash flood, move to higher ground right away. Do not wait for instructions to move.

You should evacuate under the following conditions:

  • If you are directed by local authorities to do so. Be sure to follow their instructions.
  • If you live in a mobile home or temporary structure; such structures are particularly hazardous during hurricanes no matter how well fastened to the ground.
  • If you live in a high-rise building—hurricane winds are stronger at higher elevations.
  • If you live on the coast, on a floodplain, near a river, or on an inland waterway.
  • If you feel you are in danger.

If you are unable to evacuate, go to your safe room. If you do not have one, follow these guidelines:

  • Stay indoors during the hurricane and away from windows and glass doors, even if they are covered.
  • Close all interior doors – secure and brace external doors. Closed doors will help prevent damaging hurricane winds from entering rooms.
  • Keep curtains and blinds closed. Do not be fooled if there is a lull; it could be the eye of the storm – winds will pick up again.
  • Take refuge in a small interior room, closet, or hallway on the lowest level.
  • Lie on the floor under a table or another sturdy object.

Take Action After a Hurricane

After the impact of a hurricane or tropical storm, stay alert for extended rainfall and flooding, even after the hurricane or tropical storm has weakened.

Avoid Injuries When Returning to Your Home

  • Continue listening to a NOAA Weather Radio or the local news for the latest updates.
  • Stay alert for extended rainfall and subsequent flooding even after the hurricane or tropical storm has ended.
  • If you evacuated, return home only when officials say it is safe.
  • Drive only if necessary and avoid flooded roads and washed-out bridges. Stay off the streets. If you must go out, watch for fallen objects, downed electrical wires, and weakened walls, bridges, roads, and sidewalks.
  • Stay away from loose, dangling, or downed power lines and report them immediately to the power company.
  • Inspect your home for damage. Take pictures of damage, both of the building and its contents, for insurance purposes. If you have any doubts about safety, have your residence inspected by a qualified building inspector or structural engineer before entering.
  • If you smell gas or hear a blowing or hissing noise, open a window and get everyone outside quickly. Turn off the gas, using the outside main valve if you can, and call the gas company. If you turn off the gas for any reason, it must be turned back on by a professional.
  • Check for sewer and water pipe damage.  If you suspect sewage lines are damaged, avoid using the toilets and call a plumber. If water pipes are damaged, contact the water company and avoid using water from the tap.
  • Use battery-powered flashlights in the dark and when examining buildings. Do NOT use candles.
  • Watch your pets closely and keep them under your direct control.
  • Use extreme caution when encountering debris.
  • Wear protective clothing and be cautious when cleaning up to avoid injury.
  • Use the telephone only for emergency calls.
  • Never use a generator inside homes, garages, crawlspaces, sheds, or similar areas, even when using fans or opening doors and windows for ventilation. Deadly levels of carbon monoxide can quickly build up in these areas and can linger for hours, even after the generator has shut off.
  • If you have become separated from your family, use your family communications plan or contact the American Red Cross at 1-800-RED-CROSS/1-800-733-2767 or visit the American Red Cross Safe and Well website.
  • The American Red Cross also maintains a database to help you find family. Contact the local American Red Cross chapter where you are staying for information. Do not contact the chapter in the disaster area.
  • If you cannot return home and have immediate housing needs. Text SHELTER + your ZIP code to 43362(4FEMA) to find the nearest shelter in your area (example: shelter 12345).

Hurricane Key Terms
Evacuation order
This is the most important instruction people affected by hurricanes will receive. If issued, leave immediately.
The eye is the calm center of a hurricane. Don't be fooled if wind and rain stop during a hurricane. You may just be in the eye of the storm. Listen to the radio to find out when the storm has really passed.
A tropical cyclone in which the maximum sustained surface wind (using the US 1-minute average) is 74 mph (64 knots) or more.
Hurricane Warning
An announcement that sustained winds of 64 knots (74 mph or 119 km/hr) or higher are expected somewhere within the specified area in association with a tropical, subtropical, or post-tropical cyclone. Because hurricane preparedness activities become difficult once winds reach tropical storm force, the warning is issued 36 hours in advance of the anticipated onset of tropical-storm-force winds. The warning can remain in effect when dangerously high water or a combination of dangerously high water and waves continue, even though winds may be less than hurricane force.
Hurricane Watch
An announcement that sustained winds of 64 knots (74 mph or 119 km/hr) or higher are possible within the specified area in association with a tropical, subtropical, or post-tropical cyclone. Because hurricane preparedness activities become difficult once winds reach tropical storm force, the hurricane watch is issued 48 hours in advance of the anticipated onset of tropical storm force winds.
Storm Surge
An abnormal rise in sea level accompanying a hurricane or other intense storm. Storm surge is estimated by subtracting the normal or astronomic high tide from the observed storm tide.  Storm surge can reach heights well over 20 feet and can span hundreds of miles of coastline.
Storm Tide
The actual level of sea water resulting from the astronomic tide combined with the storm surge.
Tropical Cyclone
A tropical cyclone is a rotating, organized system of clouds and thunderstorms that originates over tropical or subtropical waters and has a closed low-level circulation
Tropical Depression
A tropical cyclone with maximum sustained winds of 38 mph (33 knot) or less.
Tropical Storm
A tropical cyclone with maximum sustained winds of 39 mph (34 knots) to 73 mph (63 knots).
Tropical Storm Warning
An announcement that sustained winds of 34 to 63 knots (39 to 73 mph or 63 to 118 km/hr) are expected somewhere within the specified area within 36 hours in association with a tropical, subtropical, or post-tropical cyclone.
Tropical Storm Watch
An announcement that sustained winds of 34 to 63 knots (39 to 73 mph or 63 to 118 km/hr) are possible within the specified area within 48 hours in association with a tropical, subtropical, or post-tropical cyclone.

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