WASHINGTON —Excessive heat is the No. 1 weather killer in the United States, and it’s at its most dangerous when it doesn’t cool down at night. The current heat wave over California, Nevada, Arizona and New Mexico has temperatures hitting triple digits, with little relief at night. Hot weather is also baking the rest of the far West, including Washington, Oregon, Idaho and parts of Utah and Montana.
Q: What’s so disturbing about this current heat wave?
A: It’s unrelenting stubbornness. There is no relief at night. Phoenix set a record for highest nighttime temperature: 91. Las Vegas has gone three days without getting below 90, according to readings at the airport. “Nighttime heat is especially bad,” said Eli Jacks, chief of fire and public weather services at the National Weather Service. “Not to get below 90 is crazy.”
Q: What’s so dangerous about that?
A: If you aren’t in an air-conditioned place, “your body never has a chance to recover” at night, Jacks said. Normally the “feels-like” index — which factors in temperature and humidity — has to get to 80 degrees or below for your body to recover from the daytime heat, he said.
Q: How do heat waves compare to other weather killers?
A: In recent years, heat has been more deadly than other weather extremes in the United States. The Centers for Disease Control and Prevention indicate that on average, 658 people die each year from too much heat.
Q: Who is most at risk?
A: The elderly and children. The elderly make up 36 percent of heat deaths in the past decade, according to the CDC. And of all the excessive heat deaths, 69 percent are men.
Q: So what’s causing all this?
A: Part of it is normal summer heat spurts, said meteorologist Kenneth James of the Weather Prediction Center in College Park, Md. But there’s another factor and that’s the jet stream. What’s happening now is “a really big kink in the jet stream, about as big as you can see anytime, covering the whole western U.S.,” said heat wave expert Ken Kunkel, a professor of atmospheric sciences at North Carolina State University. To the west of the kink, in Arizona and Nevada, there’s a high pressure system just parked there with stagnant heat, Kunkel said. And to its east are cool — even record cool — temperatures in Texas, he said.
Q: When will it end?
A: The extreme heat should continue for about a week, but it won’t set records, James said.
Q: Is this global warming?
A: No single event can be blamed solely on man-made global warming, scientists and meteorologists say. But this is the type of heat wave that scientists have long said will be more common as the world warms. Some, but not all, scientists also theorize that the jet stream is having more of these crazy kinks lately because of a warming Arctic and melting sea ice.