What to Know About Upcoming Heat Waves and How to Protect Yourself as Earth Gets Hotter

More than 700 people die from extreme heat each year in the United States — and with a record-shattering heatwave sweeping across the country, staying safe from the soaring temperatures is more important than ever.

On Monday alone, both Seattle and Portland set new records for high temperatures (107 and 115 degrees, respectively), and in recent weeks, Phoenix has seen temperatures of 118 degrees, while Palm Springs residents have had to deal with 123-degree heat.

"It is quite unusual to see so many records being broken even before the official start of the summer season," Kristina Dahl, senior climate scientist with the Union of Concerned Scientists, recently told NPR. "We often call heat the silent killer. Of all of the types of extreme weather, people die from extreme heat the most. It typically kills more people in a given year than something like hurricanes or droughts."

In order to stay safe, it's best to know if you fall in a group that the National Weather Service deems "particularly vulnerable": young children and infants, pregnant women, people with chronic medical conditions and older people, in particular those on medication and/or with pre-existing conditions.

These groups are more susceptible to hot temperatures because their bodies are unable to regulate their body temperatures in the same way that younger, healthy adult bodies are, according to NPR.

There are also personal factors that play a role in the body's ability to cool you off, including age, obesity, fever, dehydration, heart disease, mental illness, poor circulation, sunburn and prescription drug and alcohol use, according to the Centers for Disease Control and Prevention.

Experts say that during extreme heat, it's important to drink plenty of water, even if you're not thirsty, and to wear loose-fitting, light-colored clothing. You should also be sure to never leave a child, disabled person or pet inside a locked car (advice that people should follow even in colder temperatures).

If you're outside, make sure to stay hydrated, and take breaks in the shade as often as possible while being sure to limit strenuous outdoor activities. If you're exercising outside, schedule your workout for earlier or later in the day, when temperatures will be cooler.

The CDC also warns to beware of high humidity, as sweat will not evaporate as quickly when it's very humid, which will prevent your body from releasing heat as fast as it may need to.

"If it's very humid, it becomes harder for the sweat on your skin to evaporate," Dahl told NPR. "And it's that evaporation of sweat that really provides the cooling effect to your body."

Even if you are keeping indoors during extreme heat, there are plenty of other tips to consider: do not rely on a fan as your main source of cooling, check on your friends and neighbors and don't use the stove or oven to cook, as it will make your house hotter, according to the CDC.

Those living in cities should also be aware that the sun going down doesn't mean they're in the clear.

The NOAA Weather-Ready Nation Ambassador initiative warned on Twitter of the so-called "urban heat island" phenomenon, which explains that larger cities often experience higher temperatures than surrounding areas because of all the heat-absorptive surfaces, like dark pavement and buildings.

"The upper floors of brick buildings are particularly susceptible to the dangers of excessive heat without air conditioning, because they retain heat after the sun goes down," NOAA wrote in a Twitter graphic. "The strong influence of the urban heat island on nighttime temperatures limits the ability of people to cool down and recover before the heat of the next day."

If you see someone suffering heat exhaustion, get them to a cooler, air-conditioned place, have them drink water if they're fully conscious and have them take a cool shower or use a cold compress. Symptoms include feeling faint or dizzy, excessive sweating, cool, pale or clammy skin, nausea or vomiting, a rapid and weak pulse and muscle cramps.

Signs of heat stroke, meanwhile, are similar but slightly different — and require immediate medical attention. Experts advise calling 911 if you or someone you know exhibits symptoms such as a throbbing headache, no sweating, a body temperature of about 103 degrees, red, hot, dry skin, nausea or vomiting, rapid, strong pulse and a possible loss of consciousness.

"When you're young and healthy, it's harder to listen to those early signals of heat illness that your body's trying to give you," Dahl told NPR. "And so we do, unfortunately, every year see people who are otherwise fit and healthy passing away due to extreme heat exposure."