Heat warnings blanket Canada's eastern corridor Thursday as the year's first major heat wave drags on, and even parts of Northwest Territories are feeling the burn.

Cascading across provinces since early in the morning, the severe weather alerts stretch in a patchwork from Windsor, Ont. in the southwest, up along the coasts of Lake Erie, Ontario, Huron, and Georgian Bay, past Ottawa and along the St. Lawrence River, before sweeping through the Maritimes and jumping the Cabot Strait to central and northern Newfoundland.

Maximum expected temperatures range from roughly 28 to 35 C, with areas directly touching the Great Lakes coastlines experiencing milder heat. Taking into account the humidex, parts of eastern Canada could feel 10 degrees warmer, with New Brunswick maxing out at 45.

Severe weather alerts and details for your region can be found on Environment and Climate Change Canada's weather tracker. Check your local forecast on CTVNews.ca's weather hub.

Heat near the high Arctic?

Among the heat warnings issued Thursday is an alert for Blackstone Territorial Park, a large swath of land west of Yellowknife and along the border north of Fort Nelson, B.C. In the region, residents can expect temperatures near 29 C, with overnight lows of 14 C.

Further north, the community of Fort Good Hope, N.W.T., is under an air quality advisory due to smoke, which has also reduced visibility in some cases. Residents are encouraged to limit their time outdoors and to protect themselves with the use of indoor air filters, ventilation and in the event they spend time outside, a well-constructed and fitting respirator such as an N95 mask.

Also in Arctic Canada is a fog advisory for the region of Kinnhgait, Nvt., where visibility is expected to drop to near zero.

Keeping cool is crucial

Environment Canada analysts are saying the heat event could last well into Friday, and to expect "dangerously hot and humid conditions" throughout.

The warnings carry a variety of advice for ensuring the safety of loved ones, including children and the elderly, individuals with disabilities, family, friends, neighbours and pets.

"Extreme heat can affect everyone’s health," the warning from Environment and Climate Change Canada reads. "During times of high heat, your health and the health of your family and friends can deteriorate rapidly."

Here are some of the things experts say to keep in mind:

  • For your own sake, drink plenty of water regularly throughout the day and even when you don't yet feel thirsty — dehydration, they note, can set in before you feel it. Six to eight glasses of water per day is recommended, and residents in affected areas should avoid alcoholic and caffeinated beverages.
  • Plan your day around the heat, scheduling outdoor activities for the coolest parts of the day wherever possible. Workers should take regular breaks in cool, shaded spaces.
  • Never leave people or animals inside a parked vehicle. Children and seniors should especially be kept out of hot cars.
  • Monitor yourself and others for the early signs of heat-related illness, such as feeling unwell, fatigue, thirst, cramps, fainting, swelling and headaches. Anyone feeling symptoms should relocate to an air-conditioned or cooler environment such as shade immediately, as these conditions can quickly become life-threatening, especially among those most vulnerable.
  • In the event of heat stroke, call 911 or your local emergency number immediately. Signs include confusion, unconsciousness and a halt to sweating, even with a high body temperature. While awaiting medical assistance, move the person to a cooler environment, fan them as much as possible and apply cool water to large areas of their skin. Helping cool them down right away is very important.