All thunderstorms are dangerous and produce lightning. Lightning strikes can injure, or even kill, people. Other associated dangers of thunderstorms include tornadoes, strong winds, hail and flash flooding.
- may occur singly, in clusters or in lines
- warm, humid conditions are highly favourable for thunderstorm development
- thunderstorms typically produce heavy rain for a brief period, anywhere from 30 minutes to an hour
- some of the most severe storms occur when a single thunderstorm affects one location for an extended time
- lightning's unpredictability increases the risk to individuals and to property
- lightning often strikes outside of heavy rain and may occur as far as 16 kilometres away from any rainfall
- "heat lightning" is actually lightning from a thunderstorm too far away for thunder to be heard; however the storm may be moving in your direction
- most lightning deaths and injuries occur when people are caught outdoors in the summer months during the afternoon and evening
Take protective measures
- When thunder roars, go indoors. Learn more.
- In advance of a storm:
- remove dead or rotting trees and branches that could fall and cause injury or damage during a severe thunderstorm
- Avoid the following if a thunderstorm is likely to happen in your area:
- postpone outdoor activities
- get inside a building or hard top vehicle; although you may be injured if lightning strikes your car, you are much safer inside a vehicle than outside
- disconnect electrical appliances including radios and television sets; do not touch during the storm
- rubber soled shoes and rubber tires provide NO protection from lightning; however the steel frame of a hard-topped vehicle provides increased protection if you are not touching metal
- secure outdoor objects that could blow away or cause damage
- shut windows and secure outside door
- during thunderstorms, stay away from items that conduct electricity, such as telephones, appliances, sinks, bathtubs, radiators and metal pipes
- Avoid the following places during the storm:
- natural lightning rods such as a tall, isolated tree in an open area
- hilltops, open fields, the beach or a boat on the water
- isolated sheds or other small structures in open areas
- anything metal - tractors, farm equipment, motorcycles, golf carts, etc.
- After the storm:
- remember the 30/30 lightning safety rule - go indoors if, after seeing lightning, you cannot count to 30 before hearing thunder; stay indoors for 30 minutes after hearing the last clap of thunder
What you can do if you are caught in a thunderstorm
If you are in an open area, go to a low place such as a ravine or valley. Be aware of flash floods.
If you are on open water, get to land and find shelter immediately.
If you are anywhere and you feel your hair stand on end (which indicates that lightning is about to strike), squat low to the ground on the balls of your feet. Place your hands over your ears and put your head between your knees. Make yourself the smallest target possible and minimize your contact with the ground. DO NOT lie flat on the ground.
If you are in a forest, seek shelter in a low area under a thick growth of small trees.