THURSDAY, July 18 (HealthDay News) -- Relief from the massive heat wave that has gripped the eastern half of the United States is coming, meteorologists said Thursday, but it will take a day or two before a Canadian cold front brings relief to cities along the eastern seaboard.

Although the cold front will also bring severe thunderstorms with it, the Midwest, Mid-Atlantic and Northeast should be bathed in cooler air by Saturday or Sunday, according to the U.S. National Weather Service.

The largest heat wave of the summer has parked itself over much of the United States for most of the week, with sizzling temperatures and high humidity levels making life miserable for millions.

Until the weekend comes, health experts said there are steps everyone can take to minimize their risk from extreme heat.

One essential step: Check up on elderly or ill relatives living on their own.

"Due to various reasons, the elderly are prone to suffer from the extreme heat," said Dr. Salvatore Pardo, associate chairman of the emergency department at Long Island Jewish Medical Center in New Hyde Park, N.Y.

"It is vital for loved ones and friendly neighbors to enter the home and make sure they have functioning air conditioning or access to a cool environment -- for example, a cooling center, senior center, public shopping mall -- during extreme heat events," he said. "This should be done at the beginning, during and after the extreme heat event."

Dr. Michael Ammazzalorso, chief medical officer at Winthrop-University Hospital in Mineola, N.Y., offered other potentially lifesaving tips.

Keeping the shades drawn in the daytime can keep homes cooler, he said, and "if you live in a split-level home, stay downstairs. Heat rises, so upstairs will always be hotter than your living room. Open windows upstairs if you have no air conditioning to keep the room cool, and have a fan blowing."

Alcoholic beverages dehydrate, so stick to water or beverages without alcohol, sugar or caffeine, Ammazzalorso said. Wear light, light-colored and loose clothing to stay cooler.

"Let the children play outside in the early morning or early evening when the air quality is at a healthier level and the temperatures are cooler," he added. "Head to a local swimming pool or beach to cool off, but never swim alone and be sure to observe all posted swimming advisories."

According to Ammazzalorso, signs of heat exhaustion include skin that is cool, moist and pale but may look flushed at times. Dizziness or fainting, nausea or vomiting, fatigue and headaches are also potential signs of heat exhaustion.

Symptoms of an even more serious condition known as heat stroke include red, hot and dry skin, high body temperatures (105 degrees or above), a rapid and weak pulse, rapid and shallow breathing and changes in consciousness. In these cases, call 911 immediately, Ammazzalorso said.

Precautions also need to be taken to keep your pets safe in the heat. The Humane Society of the United States recommends the following:

  • Never leave your pets in a parked car, not even for a minute and not even if the car is running and the air conditioning is working. If you see an animal in distress in a parked car, call the nearest animal shelter or police.
  • Watch the humidity, because dogs have to pant to cool down, which they can't do in high humidity.
  • Limit exercise on hot days, focusing on early morning and evening hours. Asphalt also gets very hot and can burn your pet's paws, so walk your dog on the grass when you can.
  • Give your pets shade and water if they are outside. In heat waves, add ice to your pet's water when possible. Tree shade and tarps are ideal because they don't obstruct air flow.

More information

The U.S. Federal Emergency Management Agency has more about extreme heat.