Recommendations to face a new heat wave in the US 2:24
(CNN) --
More than 40 million people are under heat alerts in the US as dangerous temperatures continue to affect parts of the country.
The heat will be centered this Friday in the south and will increase this weekend in the Pacific Northwest.
Dozens of cities across the South will likely see temperatures this Friday, including Dallas, San Antonio, Baton Rouge, New Orleans and Mobile.
In New Orleans, high humidity will combine with high temperatures to create a dangerous heat index above 110° Fahrenheit (43.4 Celsius).
Dallas will see readings of over 100 degrees Fahrenheit (37.7 Celsius) over the weekend.
Much of northern Florida is under heat advisories, including Tallahassee and Tampa.
Several cities in the United States reach record temperatures due to heat waves
In the Pacific Northwest, the first significant heat wave of the season will develop over the weekend.
Seattle and Portland are under a heat advisory starting tomorrow afternoon and running through Monday.
Portland, which has only topped 80°F (26.6°C) twice this year, is forecast to approach 100°F (37.7°C) on Sunday.
Extreme heat engulfs the US: health risks
Heat is the number one cause of weather-related deaths in the United States, and providing guidance on the likelihood of heat-related illnesses, including heat cramps, exhaustion, stroke, and possibly death, helps protect the public in hot conditions. extreme heat.
However, sometimes low temperatures at night are as much to blame as high temperatures during the day.
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What is the difference between heat exhaustion and heat stroke?
"Your body needs to cool down at night and it actually expects it while you're sleeping," said Jenn Varian, a meteorologist with the National Weather Service's Las Vegas office.
"When we have very hot night temperatures, your body just can't cool down properly, which in itself can cause complications, but it will also make you less prepared for the heat of the day."
Temperatures must drop to at least 80°F (26.6°C) for recovery to begin.
In fact, a person can lose up to two liters of fluid overnight through sweat if the temperature never drops below 85°F (29°C).
