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Weather Safety

Weather alerts are issued during periods of extreme heat or cold weather that may have an impact on an individuals health.

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Cold Weather

It is important to be prepared in the winter time for the cold weather conditions. Exposure to cold temperatures can stress the body and make it more susceptible to cold-related illnesses. The four environmental conditions that cause cold-related stress are:

  • low temperatures
  • high/cool winds
  • dampness
  • cold water

Wind chill, a combination of temperature and wind speed, is also a critical factor to consider when spending time outside. A dangerous situation of rapid heat loss may arise for any individual exposed to high winds and cold temperatures.


When body temperature drops even a few degrees below its normal temperature of 37°C, the blood vessels constrict, which decreases peripheral blood flow in order to reduce heat loss from the surface of the skin. Shivering, the rapid contraction of the skeletal muscles, generates heat production that can temporarily increase body temperature.

Infants and the elderly are particularly at risk for cold-related illnesses, but anyone can be affected. Outdoor workers, outdoor athletes, the homeless, people on prescription medication and those with circulatory problems are also at a higher risk.


Frostnip occurs when skin is exposed to cold wind causing the skin to turn white. This usually occurs in extremities fur ther from the hear t that are exposed to cold or winds. This is considered the first stage of frostbite and results when blood vessels close to the skin constrict, reducing blood flow to the area in an attempt to preserve the body’s core temperature. Frostnip does not usually damage affected areas permanently, although long-term sensitivity to both heat and cold can sometimes follow.Areas affected by frostnip should be treated by re-warming the area with a warm object or hand, not hot water.


Frostbite occurs when an area of the body actually freezes including skin, muscles tendons, blood vessels and nerves. The affected skin is often hard, waxy feeling, and use of the area is lost temporarily, and in severe cases, permanently. Purplish, bloodfilled blisters may appear in severe cases and nerve damage may result in the loss of feeling and/or movement. Frostbite may occur without hypothermia (see below) where the affected area does not have sufficient circulation or is not properly clothed. Winds also increase the risk of frostbite as heat loss from the body is more rapid in windy conditions.Treatment should involve warming the body and removing restrictive clothing from the affected area as well as seeking medical treatment. However, it is NOT recommended that the affected area be rubbed, immersed in hot water or that blisters be broken.


Often confused with frostbite or trenchfoot, chilblains are ulcers affecting the extremities as a result of prolonged exposure to cold and humidity. This exposure causes damage in the capillary beds which can result in symptoms of redness, itching, blister and inflammation. Chilblains can be prevented by keeping the feet and hands warm in cold weather.


Hypothermia occurs when the body’s core temperature drops below 35°C /95°F, at which point your body cannot regain the heat being lost. Hypothermia can take a victim by surprise since it can occur above the freezing point. Wind, physical exhaustion and wet clothing all make a person more prone to hypothermia. Symptoms of hypothermia include shivering, exhaustion, confusion, fumbling/uncoordinated movements, memory loss, slurred speech and drowsiness. Infants may also show signs of very low energy and bright red, cold skin. Persons experiencing hypothermia should be treated by getting their body warm again via heated shelter, clothing (removing wet clothing), warm non-alcoholic beverages and medical treatment. CPR is required for those without pulse and mouth-to-mouth resuscitation for those not breathing.

Plan Ahead

  • Be aware of the weather forecast, dress accordingly and be ready for extreme cold weather events that may result in an emergency.
  • Prepare your home and car for extreme cold weather events by stocking emergency supplies such as: food that does not require cooking or refrigeration, drinking water, back-up power supply (e.g. generator), clothing and blankets, etc.

Dress Warmly and Stay Dry

  • An outer layer of tightly woven clothing (wind resistant) is preferred to reduce heat loss from wind.
  • Wool, silk or polypropylene will hold more body heat than cotton.
  • Sweating will increase heat loss, so remove layers whenever you feel too warm.
  • Change out of wet clothing as soon as possible.
  • Avoid time outdoors when temperatures are extremely low.

Heat Your Home Safely and Adequately

  • Ensure your home is adequately insulated, meeting or exceeding the Ontario Building Code requirements.
  • Install smoke detectors and carbon monoxide detectors near fireplaces and stoves.
  • Generators must be used outdoors, as they produce carbon monoxide.
  • Conserve heat by avoiding opening doors and windows as much as possible. Unused areas can also be closed off.

Monitor Body Temperature

  • Infants lose body heat more easily than adults and are unable to make enough heat by shivering, so DO NOT leave infants alone in a cold room.
  • The elderly produce less body heat due to their slower metabolism and lower physical activity levels and therefore should monitor their body temperature and/or be checked on regularly.
  • Persons who are often outdoors (e.g. outdoor workers, athletes) during cold weather should acclimatize their bodies to the temperature.

Drink Plenty of Fluids

  • Dehydration can occur through the skin and lungs as a result of dryness in the air. Persons exposed to the cold should drink plenty of fluids to avoid decreased blood flow.
  • Avoid drinking liquids that contain alcohol, caffeine or large amounts of sugar- these drinks actually cause you to lose more body fluid.

Pace Yourself

  • Your body is already working hard to stay warm, so dress warmly and work slowly when exposed to the cold.
  • Persons with heart disease or high blood pressure should avoid overexertion.

Cold Weather Alerts

Hot Weather

Heat Warnings

The HNHU declares heat warnings when prolonged exposure to outdoor conditions could prove dangerous to public health. Environment and Climate Change Canada’s meteorological services notifies Public Health when there is an impending heat event forecast for our area.

The HNHU will then issue a Heat Warning or Extended Heat Warning based on the duration and intensity of the expected conditions:

  • Heat Warning – when forecast temperatures are expected to be at least 31°C and overnight temperatures are at or above 20°C for two days or the Humidex is forecasted to be at least 40°C for two days.
  • Extended Heat Warning – When forecast temperatures are expected to be at least 31°C and overnight temperatures are above 20°C for three or more days or Humidex is at least 40°C for three or more days.

Heat Cramps

Symptoms of heat cramps include:

  • Painful muscle spasms, usually in the legs but is possible in abdomen
  • Heavy sweating

To treat heat cramps:

  • Apply firm pressure on cramping muscles or gently massage to relieve spasm.
  • Give sips of water.
  • If nausea occurs, discontinue sips of water, move person to a cooler place to rest in a comfortable position. Observe the person carefully for changes in condition.

Heat Exhaustion

 Symptoms of heat exhaustion include:

  • Heavy sweating
  • Weakness
  • Cold, pale and clammy skin
  • Weak pulse
  • Fainting and vomiting
  • Core temperature usually 38.8°C or higher, (but normal temperature is possible)

To treat heat exhaustion:

  • Get person out of the sun. Move person to a cooler environment.
  • Lay person down and loosen clothing.
  • Apply cool wet cloths. Give sips of water.
  • If nausea occurs, discontinue sips of water. If vomiting continues, seek immediate medical attention.

Heat Stroke

Signs and symptoms of heat stroke include:

  • High body temperature of 41°C (or higher).
  • Hot, dry skin, rapid and strong pulse, possible unconsciousness.
  • Dizziness, throbbing headache, confusion, restlessness, unconsciousness, or coma.
  • Possible convulsions, nausea, vomiting.

To treat heat stroke:

  • Severe medical emergency – Call 911 immediately and do not give fluids.
  • If immediate medical help is not possible, provide the following care:
    • Move person to a cooler area.
    • Remove or loosen outer clothing.
    • Reduce body temperature by using lukewarm (not cold) water to bathe/sponge the person.

Protecting yourself in hot weather

A combination of high heat and high humidity can be dangerous. Anyone who experiences physical distress because of extreme temperatures should seek medical attention immediately, either by calling 911 or by going to the nearest emergency department. 

  • Drink plenty of water before feeling thirsty and avoid alcoholic and caffeinated beverages
  • Limit time outdoors when the UV Index (ultraviolet ray strength) is most intense, between 11am – 4pm
  • Apply Sunscreen with SPF 30 (or higher) 20-30 minutes before going outside to ensure absorption – Re-apply every 2-3 hours
  • Wear a hat and light, loose-fitted clothing
  • Avoid heavy physical activity outdoors
  • Seek shade at a park or greenspace or use an umbrella
  • Cool off in an air-conditioned space when available
  • Use a fan – you can place a bowl of cold water or ice in front of an electric fan to create a cool breeze
  • Take a cool bath or shower
  • Keep your home cool
    • Close window shades during the hottest part of the day to reduce direct sun exposure
    • Avoid cooking during the hottest period or the day
    • Unplug large electronics such as televisions that produce heat
  • NEVER leave children or pets in a vehicle
  • Visit one of the cooling centres listed here

Hot Weather Alerts

More information

Learn about public weather warnings and visit the following websites for more information: