Skip to main content

Hurricane or tropical storm

Hurricane season is the time of year when hurricanes and tropical storms form in the Atlantic Ocean and Gulf of Mexico. Hurricane season lasts from June through November, with the most activity taking place from August through September. If a hurricane is strong enough, affected areas could be asked to evacuate.

Differences between a warning and a watch

More +

The formation of a hurricane

The formation of a hurricane happens in three stages:

  1. Tropical depression – when maximum sustained surface winds are up to 38 mph (33 knots).
  2. Tropical storm – an organized system of strong thunderstorms with a defined circulation and maximum sustained winds of 39–73 mph (34–63 knots).
  3. Hurricane – when sustained winds in a tropical cyclone equal or exceed sustained 74 mph (64 knots) or greater.
  • Eye – center of a hurricane with light winds and partly cloudy to clear skies. The eye is usually around 20 miles in diameter, but can range between five and 60 miles.
  • Eye wall – location within a hurricane with the most damaging winds and intense rainfall.
  • Storm surge – abnormal rise of water caused by a storm, over and above the predicted astronomical tide. It’s the change in the water level due to the storm. Storm surge is caused primarily by the strong winds in a hurricane or tropical storm. All locations along the U.S. East and Gulf coasts are vulnerable to storm surge because the surge can make its way well inland from the coastline.

Hurricane scale

  • Category I – 74–95 mph winds with 4–5 ft. storm surge and minimal damage
  • Category II – 96–110 mph winds with 6–8 ft. storm surge and moderate damage
  • Category III – 111–130 mph winds with 9–12 ft. storm surge and major damage
  • Category IV – 131–155 mph winds with 13–18 ft. storm surge and severe damage
  • Category V – 155+ mph winds with 18+ ft. storm surge and catastrophic damage

How to prepare for a hurricane or tropical storm

  • Have a family emergency plan.
  • Know your evacuation route and where you’ll go if told to evacuate.
  • Fill-up your car’s gas tank in case you have to evacuate.
  • Make a go bag of emergency supplies in case you have to leave in a hurry.
  • Protect your windows from high winds by covering them with pre-cut plywood or hurricane shutters.
  • Bring in all outdoor furniture, decorations, garbage cans, and any other outdoor item that is not secured.
  • Keep all trees and shrubs trimmed.


Sign up for ReadyPhiladelphia, the region’s emergency text and email alert system. The alerts are free but standard text messaging rates may apply.

Hurricane mobile app

The American Red Cross Hurricane App can help you prepare for a hurricane. The app allows you to track storms, prepare your family and home, find help, and let others know you are safe. The app is available to download on Android or Apple devices.


Hurricanes, tropical storms, nor’easters, and other coastal storms can also cause flooding and utility interruptions. Visit the flood page to learn about flood safety tips.