Environmental Health

Extreme Cold Weather Alerts

The Medical Officer of Health will issue Extreme Cold Weather Alerts when Environment Canada forecasts a temperature of -15 °C or colder or a wind chill of -20 or colder in the City of Toronto.

Extreme Cold Weather Alerts may also be issued at warmer temperatures when Environment Canada's weather forecast includes factors that increase the impact of cold weather on health such as precipitation, low daytime temperatures, or several days and nights of cold weather in a row.

During Extreme Cold Weather Conditions

Please call or visit vulnerable family, friends and neighbours, especially isolated seniors to make sure they are alright.

Other groups at risk include people with pre-existing heart conditions or chronic respiratory illness, infants and young children, people on certain medications, people who work or do physical activities outside for extended periods, and those who are marginally housed or homeless.

Health Impacts of Cold Weather Exposure

Frostnip and frostbite

Frostnip and frostbite occur when skin and other tissues freeze, and die because blood and oxygen can no longer circulate. Frostnip and frostbite mainly affect extremities such as fingers and toes. Skin may appear waxy, grey, and cold to the touch. In severe cases, amputation may be needed.


Hypothermia occurs when the body's core temperature drops below 35 °C. At first, hypothermia causes shivering, confusion, and stumbling. With longer exposure, hypothermia can have severe consequences including organ failure and death.

Heart Conditions

People with heart problems are more likely to be hospitalized or die from their condition after periods of very cold weather.

Tips to stay healthy in cold weather

Dress in layers and cover exposed skin

  • Make sure your outer layer is waterproof and windproof
  • Wear a hat
  • Choose warm mittens instead of gloves
  • Wear warm, waterproof boots
  • Frostbite can happen in less than a minute so cover as much exposed skin as possible


Stay Dry

  • If you get wet, change into dry clothing as soon as possible


Seek Shelter

  • Depending on the wind chill, exposed skin can freeze in minutes
  • Consider rescheduling outdoor activities or limiting time outdoors, especially if it is windy
  • Check the weather report before you go outside
  • Know the heated buildings in your neighbourhood i.e. library, malls, etc.


Avoid drinking alcohol

  • Alcohol increases blood flow, making you feel warm even though you are losing body heat

Stay active and safe

  • Watch out for hazards
  • Winter boots should be comfortable with a wide and low heel
  • Keep your home walkways free of ice and snow
  • Wear bright-coloured clothing in snowy weather


Plan ahead and get your home ready for winter:

  • Heat your home to 21 ºC
    • For renters: Toronto has a bylaw that requires landlords to provide heating up to at least 21 ºC between September 15 and June 1 of each year (Municipal Code Chapter 497 Article 1
  • Conduct regular maintenance, including ensuring your heating system is working properly.
  • Prepare for the possibility of power outages



If you have a car, make sure it has a survival kit including a first aid kit and water.

Plan ahead for groups and organizations

Groups and organizations should develop a plan for how they will handle cold weather, to ensure that everyone will stay safe.

 What to include in your plan:

  • Checking the weather forecast
  • Rescheduling or limiting outdoor activities during Extreme Cold Weather Alerts or other wintry conditions
  • Ensuring availability of warm drinks
  • Ensuring children are dressed warmly, covering exposed skin
  • Scheduling warm-up breaks for outdoor workers
  • Training for staff to recognize and treat symptoms of frostbite and hypothermia


Groups and organizations should also develop an emergency plan in case of power outage during the winter.