Learn About Severe Weather

Thunderstorms, tornadoes, hail, blizzards, high winds and heavy rain can develop quickly and hit hard – posing a threat to life and property. If you are like most Canadians you have probably had to clean up after these storms and you know the damage they cause. Some problems cannot be prevented. High winds will topple trees and heavy rains will cause rivers to flood. But some damage can be avoided or at least reduced, if you take a few simple precautions such as knowing the type of storms common to your area and what time of year they are likely to strike. The purpose of this booklet is to help you prepare for severe weather by listing a few steps which you can take to protect your family, yourself, and your property when a severe storm hits your area.

Listen for the Warnings

Environment Canada monitors the weather 24-hours a day, seven days a week. If a severe storm is on the horizon, the weather service issues watches, advisories and warnings through national, regional and local radio and television stations, and Environment Canada’s Weather Radio.

  • Weather Watch: conditions are favourable for a severe storm, even though one has not yet developed.
  • Weather Advisory: the actual or expected weather conditions may cause concern or general inconvenience, but do not pose a serious enough threat to warrant a weather warning.
  • Weather Warning: severe weather is happening or hazardous weather is highly probable.

If a weather warning is issued for a tornado, it means that one or more tornadoes have been observed or are forecast for the specified area. Other warnings include those for a severe thunderstorm, blizzard, high winds, heavy snow, snow squall, heavy rain and heavy freezing rain.

Be Prepared

Storms such as tornadoes often strike too quickly to allow you to choose a shelter or pack an emergency kit. You may want to have a plan that outlines where you will go and how you will keep in touch with members of your family if a severe storm hits. Municipal, provincial and territorial emergency measures organizations can provide valuable advice to help you prepare for emergencies. Choose your shelter area A basement, storm cellar or a closet beneath the stairs are good places to take shelter in the event of a severe storm. If none of these is available, sit underneath a sturdy piece of furniture on the ground floor in the centre of the building away from the outside walls and windows. Be sure you discuss the shelter area with your family.

Pack an emergency kit

This should include food, clothing, blankets, medication, water purification tablets and first-aid and tool kits as well as flashlights and a battery-powered radio – with extra batteries for both.

Reduce the hazards

Trim dead or rotting branches and cut down dead trees to reduce the danger of these falling on your house. You may also want to consider checking the drainage around the house to reduce the possibility of your basement flooding after a heavy rain. Choose a place to meet When a severe storm strikes, members of your household may be at work, school or a friend’s place. To avoid unnecessary worry, plan a meeting place or some system of communicating with one another to check that everyone is safe.

When a Severe Storm is Forecast

During the season when some of the severest storms, such as tornadoes or blizzards are likely to occur in your area, listen to the local radio or television stations for severe weather warnings and advice. You may want to make sure you have a battery-powered radio on hand as the electricity frequently fails during a severe storm. Secure everything that might be blown around or torn loose – indoors and outdoors. Flying objects such as garbage cans and lawn furniture can injure people and damage property. If hail is forecast, you may want to protect your car by putting it in the garage.

Never venture out in a boat. If you are on the water and you see bad weather approaching, head for shore immediately. Always check the marine forecast first before leaving for a day of boating and listen to weather reports during your cruise. If you are advised by officials to evacuate, do so. Take your emergency kit with you. If you are outdoors when a storm hits, take shelter immediately. Stay calm. You will be able to cope better with emergencies.



Tornadoes form suddenly, are often preceded by warm humid weather and always produced by thunderstorms – although not every thunderstorm produces a tornado. There are warning signs, including:

  • Severe thunderstorms with frequent thunder and lightning
  • An extremely dark sky sometimes highlighted by green or yellow clouds
  • A rumbling sound, such as a freight train might make or a whistling sound such as a jet aircraft might make
  • A funnel cloud at the rear base of a thunder cloud often behind a curtain of heavy rain or hail

Tornadoes are violent windstorms characterized by a twisting funnel-shaped cloud which forms at the base of cloud banks and points towards the ground. Tornadoes usually move over the ground at anywhere from 20 to 90 km/h and often travel from the southwest to the northeast. They are erratic and can change course suddenly. It is not a good idea to chase tornadoes. Generally speaking, May to September are prime tornado months. Tornadoes usually hit in the afternoon and early evening but they have been known to strike at night too. Canada has several high risk areas including Alberta, southern Ontario, southwestern Quebec and a band of land which stretches from southern Saskatchewan and Manitoba through to Thunder Bay, Ontario. There are also tornado zones in the interior of British Columbia and in western New Brunswick. Things to do in a tornado

  • If you live in one of Canada’s high-risk areas or zones, you should listen to your radio during severe thunderstorms. As a rule, when Environment Canada issues a tornado warning, radio stations broadcast it immediately. If you hear that a tornado warning has been issued for your area, take cover immediately. If you are at home, go to the basement or take shelter in a small interior ground floor room such as a bathroom, closet or hallway. Failing that, protect yourself by taking shelter under a heavy table or desk. In all cases, stay away from windows and outside walls and doors.
  • If you are at the office or in an apartment building, take shelter in an inner hallway or room, ideally in the basement or the ground floor. Do not use the elevator and stay away from windows. Avoid buildings such as gymnasiums, churches and auditoriums with freespan roofs. These roofs do not have supports in the middle and may collapse if a tornado hits them. If you are in one of these buildings take cover under a sturdy structure.
  • Do not get caught in a car or mobile home. More than 50 per cent of all deaths from tornadoes happen in mobile homes. Take shelter elsewhere – such as a building with a strong foundation. If no shelter is available, then lie down in a ditch away from the automobile or mobile home.
  • If you are driving and spot a tornado in the distance, try to get to a nearby shelter. If the tornado is close by, get out of your car and take cover in a low-lying area or even under an underpass on a freeway. Crawl right up the bank to just under the road of the overpass. If a tornado seems to be standing still then it is either travelling away from you or heading right for you.
  • In all cases, get as close to the ground as possible, protect your head and watch out for flying debris. Small objects such as sticks and straws can become lethal weapons when driven by a tornado’s winds.

Severe Thunderstorms – Lightning, Heavy Rain and Hail

A thunderstorm develops in an unstable atmosphere when warm moist air near the earth’s surface rises quickly and cools. The moisture condenses to form rain droplets and dark thunder clouds called cumulonimbus clouds. These storms are often accompanied by hail, lightning, high winds, heavy rain and tornadoes. Thunderstorms are usually over in an hour, although a series of thunderstorms can last for several hours.


The air is charged with electricity during a thunderstorm. The most striking sign of this is lightning. Bolts of lightning hit the ground at about 40,000 kilometres per second – so fast that the lightning appears to be a single main bolt with a few forks when actually the opposite is true. The main bolt is a whole series of lightning strikes all taking the same path but at such a pace that the eye cannot distinguish between them. To estimate how far away the lightning is, count the seconds between the flash of lightning and the thunderclap. Each second is about 300 metres. If you count fewer than five seconds, take shelter immediately. Lightning is near and you do not want to be the tallest object in the area. At the office or house.

  • If indoors, stay there but away from windows, doors, fireplaces, radiators, stoves, sinks, bathtubs, appliances, metal pipes, telephones and other materials which conduct electricity (You can use a cellular telephone).
  • Unplug radios and televisions.
  • Do not go out to rescue the laundry on the clothesline as it conducts electricity.


  • Take shelter in a building or depressed area such as a ditch or a culvert but never under a tree.
  • Do not ride bicycles, motorcycles or golf carts or use metal shovels or golf clubs as they conduct electricity.
  • If swimming or in a boat, get back to shore immediately.
  • If caught in the open, do not lie flat but crouch in the leap frog position and lower your head.
  • If you are in a car, stay there but pull away from trees which might fall on you.

Heavy rain

A heavy rain fall can result in flooding. This is particularly true when the ground is still frozen or already saturated from previous storms. Floods may also result if a heavy rain coincides with the spring thaw.

  • If you know there is flooding or the possibility of flooding in your area, keep your radio on to find out what areas are flooded, what areas are likely to be flooded as well as what roads are safe, where to go and what to do if the local emergency team asks you to leave your home.
  • Generally speaking, it is a good idea to avoid driving through flooded roads and underpasses. The water may be a great deal deeper than it looks and you could get stuck. You may also want to avoid crossing bridges if the water is high and flowing quickly.


Hail forms when updrafts in thunderclouds carry raindrops upwards into extremely cold areas of the atmosphere. The raindrops freeze and are bounced around in the powerful winds within thunderclouds while new layers of ice are added. Eventually, the hailstones grow too heavy to be supported by the updrafts and fall to the ground. Some hailstones are the size of peas while others can be as big as grapefruits.

Take cover when hail begins to fall. Do not go out to cover plants, cars or garden furniture or to rescue animals. Hail comes down at great speed, especially when accompanied by high winds. Although no-one in Canada has ever been killed by hail, people have been seriously injured by it.


Blizzards come in on a wave of cold Arctic air, bringing snow, bitter cold, high winds and poor visibility. In Canada, blizzards are most common in the southern Prairies, the Maritimes and the eastern Arctic. On average, the storms and cold of winter kill more than 100 people every year. That is more than the total number of people killed by hurricanes, tornadoes, floods, lightning, and extreme heat. At home If you live in a rural community located in one of the areas where blizzards are frequent, you may want to consider stocking up on heating fuel, ready-to-eat food as well as battery-powered flashlights and radios – and extra batteries.

  • When a blizzard is forecast, leave your radio on. If you are on a farm with livestock, bring the animals into the barn. Make sure they have plenty of water and food. You may also want to string a lifeline between your house and any outbuildings which you may have to go to during the storm.
  • When a blizzard hits, stay indoors. If you must go to the outbuildings, dress for the weather. Outer clothing should be tightly woven and water-repellent. The jacket should have a hood. Wear mittens – they are warmer than gloves – and a hat, as most body heat is lost through the head.
  • In wide open areas, visibility can be virtually zero. You may easily lose your way. If a blizzard strikes, do not try to walk to another building unless there is a rope to guide you or something you can follow.

In your car As a rule, it is a good idea to keep your gas tank almost full during the winter and to have extra windshield washer fluid and anti-freeze on hand. You may want to put together two small emergency kits – one to put in the trunk of your car and the other in the cab of the car. The trunk kit should include:

  • Shovel, sand, or salt or kitty litter
  • Tow chain and booster cables
  • Fire extinguisher, warning light or flares
  • Extra clothing, including mittens, hats and boots

The kit in the cab of the car should include:

  • Flashlight
  • Blanket
  • First aid kit
  • Matches, candles (in a deep can to warm hands or heat a drink) and emergency food pack

If you do not already have a cellular telephone – and if they work in your area – you may want to consider having one in your car for emergencies. If you must travel during a snow storm, do so during the day and let someone know your route and arrival time. If your car gets stuck in a blizzard, remain calm and stay in your car. Keep fresh air in your car by opening the window slightly on the sheltered side – away from the wind. You can run the car engine about 10 minutes every half hour if the exhaust system is working well. Beware of exhaust fumes and check the exhaust pipe periodically to make sure it is not blocked with snow. (Remember – you can’t smell potentially fatal carbon monoxide fumes.)

Finally, to keep your hands and feet warm exercise them periodically. In general, it is a good idea to keep moving to avoid falling asleep. If you do try to shovel the snow from around your car avoid over-exerting yourself as shovelling and bitter cold can kill. Keep watch for traffic or searchers.


Hurricanes are violent tropical storms which blow up from the Caribbean and hit eastern Canada usually between June and November with September being the peak month. The east and west coasts, however, do get fall and winter storms which have hurricane force winds. Hurricanes cause more widespread damage than tornadoes because they are bigger. Some are as large as 1,000 kilometres across. In Canada, heavy rain and flooding are usually greater hazards than strong winds – although the winds are still strong and potentially dangerous. If a hurricane warning has been issued, and you live on the coast or in a low-lying area near the coast, you are advised to move inland and to higher ground. The high winds create huge waves at sea which when they reach the shore may become tidal waves or storm surges. Do not go down to the water to watch the storm. Most people who are killed during hurricanes are caught in large waves, storm surges or floodwaters. As a rule hurricanes move slowly and batter communities for several hours. If the eye of the hurricane passes over, there will be a lull in the wind lasting from two or three minutes to half an hour. Stay in a safe place. Make emergency repairs only, but remember that once the eye has passed over the winds will return from the opposite direction and with probably even greater force. A note for owners of mobile homes.

Owners of mobile homes must take special care to protect themselves and their property in the event of storms. Position your trailer near a natural windbreak such as a hill or clump of trees. As severe storms usually come in from the southwest, west or northwest, the narrow end of the trailer should face in a westerly direction to make a smaller target. Make sure your trailer is securely anchored. Consult the manufacturer for information on secure tie-down systems. Finally, when a severe storm approaches you should still seek shelter in a more secure building. Trailers are the exception to the stay indoors rule.

Emergency Survival Kit (Keep these supplies in an easy-to-find spot)

  • Flashlight and batteries (in case the lights go out)
  • Radio and batteries or crank radio (so you can listen to news bulletins)
  • Spare batteries(for radio and flashlight)
  • First-aid Kit
  • Candles and matches/lighter
  • Extra car keys and cash (including coins for telephone)
  • Important papers (identification for everyone, personal documents)
  • Food and bottled water (See “Food list” )
  • Clothing and footwear (one change of clothes per person)
  • Blankets or sleeping bags (one blanket or sleeping bag per person)
  • Toilet paper and other personal supplies
  • Medication Backpack/duffel bag (or something else to carry the emergency survival kit in, in case you have to evacuate)
  • Whistle (in case you need to attract someone’s attention)
  • Playing cards, games

Large orange garbage bags make great rain ponchos.