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:
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.
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.
If a hurricane is likely going to impact your area, you should:
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.
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 unable to evacuate, go to your safe room. If you do not have one, follow these guidelines:
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.
Evacuation order |
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This is the most important instruction people affected by hurricanes will receive. If issued, leave immediately. |
Eye |
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. |
Hurricane |
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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