top of page

Severe Thunderstorm

Florida thunderstorms are most  frequent during the afternoon and evening hours in the warm, humid spring and summer months, but they can occur year-round and they are always dangerous.  Thunderstorms may occur singly, in clusters, or in lines, and typically produce very heavy rain for a relatively brief period, anywhere from 30 minutes to an hour.  Thunderstorms can cause rapid flooding in low-lying areas.  Since thunder is generated by lightning, all thunderstorms have lightning, but they are classified as severe thunderstorms by the National Weather Service when they include one or more of the following: 

  • hail one inch or greater in diameter,

  • winds gusting in excess of 57.5 mph, or

  • a tornado.


Click HERE for the FEMA
Ready Business Severe Wind Toolkit

FEMA graphic indicating traits of severe thunderstorms, a powerful wind icon, cloud with lighting and hail icon, a flash flood and tornado icon
Graphic heading says Prepare Now in a Blue Circle


Graphic heading says Survive During the Hazard in Orange Circle


  • Keep your home "storm-ready."  Trim trees and branches near your house.  Ideally, no part of a tree should touch your home, and branches that hang over your roofline should be cut regularly.

  • Check the forecast regularly to see if you're at risk for severe weather.  Listen to local news or a NOAA Weather Radio to stay informed about severe thunderstorm watches (when the conditions are right for one to form) and warnings (when they are imminent or occurring in the area.)  

  • Sign up for Severe Thunderstorm Warnings through the AlertNassau notification system.

  • Pick a safe room in your home as your storm shelter - an interior room (with no windows) on the lowest floor where people and pets can go when severe thunderstorm warnings are issued.  A bathroom or closet can protect you from flying debris.

  • If you have time before severe weather hits, secure loose objects, close windows and doors, and move any valuable objects inside or under a sturdy structure.

  • Encourage your loved ones and neighbors to prepare for severe thunderstorms. 

  • Take free CPR training from the Medical Reserve Corps so you can help if someone is hurt during severe weather.

  • If you have time before the severe weather hits, secure loose objects, close windows and doors, and move any valuable objects inside or under a sturdy structure.

  • Continue to listen to local news or a NOAA Weather Radio to stay updated.

  • When a Severe Thunderstorm Warning is issued, damaging wind or large hail are approaching, Shelter-In-Place:  

    • At Home - Go to an interior room (with no windows) on the lowest floor.  Take your pets with you.

    • At Work or School - Stay away from windows.  Do not go to large open rooms such as cafeterias, gymnasiums or auditoriums.  

    • Outside - Go inside a sturdy, site-built structure immediately.  Sheds and storage facilities are not safe.  Taking shelter under a tree can be deadly - it puts you at a greater risk of getting struck by lightning and the tree, or heavy branches, may fall.

    • In a Vehicle - Being in a vehicle during severe thunderstorms is safer than being outside; however, drive to the closest secure shelter if there is sufficient time.

Graphic heading says Be Safe After the Hazard in Green Circle


  • Continue listening to local news or a NOAA Weather Radio to stay informed - more severe thunderstorms could be headed your way.

  • Let your family and close friends know that you're okay.  Text messages are  more reliable than phone calls.

  • After the severe weather threat has ended, check your property for damage.  Stay out of damaged buildings.  Wear long pants, a long-sleeved shirt and sturdy shoes to walk through damage and debris.  Don't let pets walk around in debris.

  • Contact local authorities if you see power lines down. 

  • If your home is damaged, take photographs and contact your insurance agent.  Beware of people who drive up and offer to repair your property.

  • Check on your neighbors.  If you come across someone who is injured, provide first aid (if you are trained and able) and call 9-1-1 to alert emergency responders.

Image with helpful tips on keeping your home storm ready
Storm-Ready Home

Keep Your Home "Storm-Ready"

National Weather Service Graphic describing Watch versus Warning.  A Thunderstorm Watch issued when a severe thunderstorm is possible, be prepared!  A Thunderstorm Warning is issued when one is happening nearby, take shelter immediately!
Image of tips for preparing a manufactured home before a storm: check tie-down anchoring, secure items around the home, turn off water and fuel lines, evacuate - it is never safe to remain in a mobile home during a severe thunderstorm or hurricane that might spawn a tornado.
Graphic of actions to take to prepare before a storm: consider threats from damaging wind, flooding, hail, and tornado; make a plan; have multiple ways to receive weather alerts; know what you need to do during and after a severe thunderstorm.
Graphic illustrating safe behavior after a storm; stay inside until it has passed, be aware of downed power lines, keep away from flood water, only run generators more than 20 feet from the home.
bottom of page