Extreme heat makes it especially hard for your body to cool down, so you need to be extra careful if you exercise or play sports when it’s baking outside.
Your brain tries to keep your body within a degree or two of 98.6 degrees Fahrenheit (37 degrees Celsius), and it does so in part by triggering sweat. When sweat dries, it carries away heat from your body’s surface.
When sweat can’t do its job — because your body is generating a lot of heat or it’s too hot and humid to cool down — you are at risk of becoming dehydrated or even getting a heat-related illness such as heat exhaustion or heat stroke.
Bharat Venkat, an associate professor at UCLA and the director of the UCLA Heat Lab, says heat can impact the entire body. “We’ll often talk about heat cramps. We’ll talk about heat exhaustion. We will talk about heat stroke,” he said. “But it’s actually much wider than that. Heat can really impact every system in our body, our hearts, our lungs.”
The higher the temperature, the harder it is for the body to stay cool, but humidity plays a big role too. High humidity makes it feel hotter than the temperature because it makes sweating less effective. There’s so much water in the air already that it can’t take up much more - including the water in your sweat.
The heat index, which factors in humidity and is included on many weather forecasts, provides a sense of how hot it really feels - and what’s dangerous for prolonged exposure or strenuous activity.
The National Oceanic and Atmospheric Administration says people should start exercising “caution” when the heat index reaches 80 to 90 degrees and “extreme caution” from 90 to 103 degrees. It labels everything over 103 “danger” or “extreme danger.”
NOAA has a chart that shows how the heat index is affected by humidity. For example, a day that is 90 degrees Fahrenheit (32 Celsius) can hit the “danger” level with 70% humidity.
“Athletes and other folks who regularly engage in strenuous activity often think that they can handle it,” UCLA’s Venkat said. “But a lot of studies have shown that we’re really bad at gauging how hot it is.”
Players and fans at the FIFA Club World Cup games taking place across the U.S. are also coping with high temperatures.
“In Europe it’s more of a dry heat and this is more of a humid heat. I think it’s going to hit them twice as hard,” fan Tyler Fernando said before Bayern Munich’s match against Benfica on Tuesday in Charlotte, North Carolina, where the temperature was 97 degrees Fahrenheit at game time.
Those at the Auckland City match against Boca Juniors in Nashville on Tuesday braved temperatures in the upper 90s. Male spectators went shirtless and fans sought sections where there was shade.
Chelsea cut short a practice session in Philadelphia, where temperatures reached the 90s.
“I always try to avoid excuse, I always try to be honest. It’s not about excuses, it’s about reality. It’s an excuse when it’s not hot, and we say it’s hot. That’s an excuse. But if it’s hot, it’s hot. But we are here, and we’re trying to do our best,” Chelsea coach Enzo Maresca said.
The NBA prospects in New York City for Wednesday’s draft aren’t under the kind of pressure the FIFA soccer players are, but they’re sweating the heatwave anyway — especially its impact on what has become a night to show off high-end fashions.
“I thought, I was coming to New York, I was expecting some nice, cool weather, but it’s going to be 99 degrees today in New York City. That’s hotter than it is back home in Texas,” said Liam McNeeley, who is from Richardson, Texas.
Georgetown big man Thomas Sorber had already changed out of his pants after an outdoor event earlier Tuesday, putting on shorts for his media session at a hotel.
Little relief is expected Wednesday, so players were glad that most of their time would be spent indoors. But even just a few minutes felt like too much.
“First day I got here, I was like … I was burning up,” said South Carolina forward Collin Murray-Boyles, who wore a jacket and slacks Tuesday.
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