AYESHA RASCOE, HOST:
For much of the country, summer is off to a blistering start. A heat dome sitting over the U.S. is expanding, raising temperatures well into the 90s, even into the triple digits. And accompanying this extreme heat is unusually high humidity, which presents its own set of dangers. Ben Noll is a meteorologist with The Washington Post. He joins me now. Good morning.
BEN NOLL: Good morning.
RASCOE: So how hot and humid is it going to get in the U.S.? 'Cause here in D.C., it is hot as Hades. Can I say that (laughter)?
NOLL: Yeah. Look, I've just run some of the latest statistics, and we're looking at about 265 million people across the country experiencing 90- or 100-degree heat over the next week. And this is interesting because I think this event can kind of interchangeably be called a heat wave or a humidity wave because it's going to be really brutally humid across the central and eastern part of the country.
RASCOE: What is causing that? Why is there so much moisture in the air?
NOLL: So the winds, in this case, are blowing up from the Caribbean Sea. So thousands of miles away, transporting kind of the weather from the Caribbean islands, from the Gulf of Mexico, right up into the United States. But it's not just that. Actually, the ocean waters in those parts of the world are warmer than average, and warmer air can hold more water vapor, and that's what millions of people across the United States are going to feel. Places like Minneapolis, Chicago, New York, Washington, Baltimore, down into the Carolinas, even up into southern Canada - places that you wouldn't normally, I guess, associate with extreme humidity - feeling honestly more like the tropics for a couple of days next week.
RASCOE: This high humidity, is that a part of climate change?
NOLL: I think it is. It is part of that bigger picture. I mean, summer - it's hot, it's humid. But you can look back, historically, at humidity over the course of many past summers and look at how that is changing. And what you find is a gradual trend toward more humidity. For the planet as a whole, the year 2024, last year, was the most humid by one particular metric of humidity measuring on record since records began in 1940. So this is a real trend, and it's kind of linked to the fact that a warmer atmosphere can basically contain, you know, more water vapor. So a warmer world actually is often a wetter world.
RASCOE: What are the specific dangers associated with high humidity?
NOLL: It makes it more challenging to cool off. The human body cools off by sweating. That sweat, which needs to evaporate off of the skin, it can't evaporate as quickly or as efficiently in an atmosphere that is very humid. So that sweat kind of lingers. It sticks around. Your body temperature starts to go up. And that's when kind of heat-related illnesses - heat stroke, heat stress - can come into the picture. So remaining kind of in an air-conditioned place, if you have access to that. Some folks may have a dehumidifier. That can help. If you don't have those two things, cool showers. If you have to work outside, you know, listen to your body. Take breaks. Drink water, preferably, and not, you know, other beverages that can actually dehydrate you. So it's kind of, you know, knowing your limits because they can kind of creep up on you fast in weather like this.
RASCOE: That's Ben Noll, a meteorologist with The Washington Post. Thank you so much for joining us.
NOLL: Yeah, thanks so much for having me.
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