01:10 - Source: CNN
What is a 'heat dome'?

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About 50 million people are dealing with extreme high temperatures and humidity

Midwest and South taking brunt of the heat next few days

CNN —  

Unless you’re lucky enough to live in the Pacific Northwest, summer’s been unflinchingly brutal this week.

The so-called heat dome – a large area of high temperatures and humidity – has been baking a good portion of the country for days and there’s no relief in sight.

The heat will continue to sear parts of the nation, right on through the weekend.

It’s not the heat, it’s the humidity

About 50 million Americans, mostly in the nation’s midsection, are now sweltering through this current wave of extreme heat and humidity. Excessive heat warnings, watches or advisories cover more than a dozen states. The Midwest and South will take the brunt of it over the next couple of days, though. Heat indexes in the triple digits are expected from Minnesota straight down to parts of Texas, according to the National Weather Service.

So that means Minneapolis, Milwaukee, Chicago, Des Moines, Omaha, Kansas City, St. Louis, Memphis, and Little Rock could be dealing with heat indexes as high as 120 degrees, CNN meteorologist Dave Hennen said.

The extreme heat will hit the Northeast, Mid-Atlantic and Southeastern states by the weekend.

Even President Barack Obama was worried about the temperatures.

“Stay safe as it heats up: Drink water, stay out of the sun, and check on your neighbors,” he tweeted from his POTUS account.

The real danger from this current heat wave could come after the sun goes down. While not generating a lot of record daytime high temperatures, this heat wave may produce a lot of record nighttime low temperatures, with lows not dropping below the mid-70s at night in a large chunk of the nation.

“Research after the deadly Chicago heat wave in the 1990s pointed to nighttime temperatures remaining very warm as a key contributor to all of the heat-related deaths,” Hennen explained. “When temperatures remain hot overnight, your body doesn’t have a chance to recover.”

Heat is one of the deadliest weather events, killing hundreds of people every year. Extreme heat results in even more heat-related illnesses.

What it actually feels like outside when you take into account the humidity and high temperature.

When extreme heat is combined with elevated humidity, it can be exceptionally dangerous. High humidity slows evaporation – or sweating – which is the body’s cooling mechanism. If the body can’t properly cool down, heat exhaustion is likely within as little as an hour. Because men sweat more than women, men are more susceptible to heat illness because they become dehydrated more quickly.

Beat the heat

Here’s some tips for staying a step ahead of the heat this summer:

Drink plenty of water. Avoid drinks with alcohol or caffeine, which will only dehydrate you faster.

Eat light meals. Avoid heavy meals that are high in protein, which cause the body to work harder to digest. Eat more carbohydrates so your body doesn’t have to use as much energy to digest.

Wear light-colored clothing, which will reflect sunlight instead of absorbing it. It could keep your body temperature down several degrees.

Studies show the best clothes to wear while exercising are none at all! This is because air needs to flow over your skin in order for sweat to cool you off – as much of it as possible. But if that’s not an option, loose-fitting clothing is your next best bet.

Find an air-conditioned place to get out of the heat. In temperatures above 80 degrees, fans won’t do you any good – they just blow more hot air around.

Heat stroke can happen very quickly after heat exhaustion settles in.

Hot months

This sizzling July just seems par for the course, not just for the United States – the United Kingdom is suffering through its own heat wave – but for the entire planet. On Tuesday, NASA announced that the first six months of 2016 were the hottest ever recorded.

Temperatures were on average 1.3 degrees Celsius (2.4 degrees Fahrenheit) higher than average between January and June this year, compared to the late 19th century, NASA said.

In total, the planet has now had 14 consecutive months of the hottest temperatures seen since records began in 1880, the U.S. National Oceanic and Atmospheric Administration (NOAA) said.

Australia, the United Kingdom, Hong Kong and Spain were some examples of places where temperatures soared more than a degree above average, as New Zealand had its hottest January to June period since records began.

Shrinking sea ice

All that record global heat has not been good for the Arctic.

Sea ice shrunk faster than normal as five out of the six first months of 2016 saw the smallest respective monthly Arctic sea ice cover since satellite records started in 1979.

“It has been a record year so far for global temperatures, but the record high temperatures in the Arctic over the past six months have been even more extreme,” sea ice scientist Walt Meier at NASA’s Goddard Space Flight Center said in a statement.

“This warmth as well as unusual weather patterns have led to the record low sea ice extents so far this year.”

CNN’s Matt Daniel, Ben Westcott and Dave Hennen contributed to this report.