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.


Exposure to extreme cold weather can be harmful to your health. Read more about cold related illness and how to stay warm and healthy this winter.

Staying Healthy in Extreme Cold Weather


Dress in layers and cover exposed skin

  • Cover as much exposed skin as possible.  Frostbite can develop over a relatively short period of time during periods of extreme cold
  • Wear waterproof and windproof outer layers
  • Wear a hat
  • Choose warm mittens instead of gloves
  • Wear warm, waterproof boots
  • Choose wool, silk or polypropylene inner layers of clothing, these materials hold more body heat than cotton


Stay Dry

  • Avoid wearing wet clothing, as you are more likely to develop hypothermia if you are cold and wet
  • Change into dry clothing as soon as possible if you get wet from precipitation, sweat or submersion in water


 Take care when outdoors

  • Check the weather report before going outside
  • Warm up by taking regular breaks in heated buildings such as libraries and malls
  • Reschedule outdoor activities and limit time outdoors if severe weather is forecast

Stay active and safe

  • Wear comfortable winter boots with a wide and low heel
  • Wear bright-coloured clothing in snowy weather
  • Notify friends or family where you will be when going on outdoor activities, such as hiking and skiing


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.