AILSA CHANG, HOST:

For about 150 million people in the U.S., the Fourth of July long weekend is bringing heat - scorching and possibly dangerous heat - across many states. Las Vegas may see its hottest temperature ever recorded in coming days. There are excessive heat warnings in Mississippi, Arkansas, Arizona, Washington and other states. And here in California, high temperatures have climbed into the triple digits, especially throughout the Central Valley, and parts of this state are facing elevated fire risks. Manola Secaira from CapRadio in Sacramento joins us now. Hi, Manola.

MANOLA SECAIRA, BYLINE: Hi.

CHANG: OK. So a lot of the West right now is under threat from this heat, but tell us a little more about what's going on in the Central Valley especially.

SECAIRA: Yeah. Yeah. So here in Sacramento, where I am at, we're seeing high temperatures pass 100 degrees every day this week. So today, we might actually reach 112 degrees, which would match our previous record for this day that was set in 1991. We might even pass it, so that's something that we're looking out for. But like you said, we're not alone. A lot of California is seeing similarly high temperatures. The National Weather Service forecasted an extreme heat risk for many parts of the state throughout this week and also into the weekend.

CHANG: But I mean, California generally does get pretty hot in the summer, so how unusual is this heat that we're seeing right now?

SECAIRA: It is true that we see high temperatures pretty typically here during the summer, so this isn't completely out of the ordinary. But what makes this different is how long it's expected to last and that it's happening in early July. So officials with the Weather Service here in Sacramento are saying we're seeing temperatures about 10 to 20 degrees above the norm for this time of year. And then another key part of this is that there's little overnight relief. In central California, that means overnight low temperatures will be somewhere in the 70s and maybe even the 80s.

CHANG: Wow.

SECAIRA: And then - yeah, so pretty warm. Medical professionals say it's more dangerous for people, especially vulnerable communities who can't get any relief from the heat even at night now. So while again, this isn't something we've never seen before, it is part of this worrying trend we see with human-driven climate change. Climate science tells us that heat waves are getting longer, more frequent and also more intense.

CHANG: Yeah. And obviously, heat also raises the risk of wild fires. So what is the outlook in California for fires at this point?

SECAIRA: The National Weather Service issued a red-flag warning that covers a huge swath of inland Northern California, which is, again, where I'm at. That means we're seeing weather that makes wildfires starting and spreading just a lot more likely. And then there's this one dangerous fire called the Thompson Fire, which is just a little bit north of Sacramento. And there, around 28,000 people are under an evacuation order. So that fire spread pretty quickly just because of the conditions we're seeing brought on by this heat.

And then on top of all that, there's the Fourth of July tomorrow, and that holiday comes with firework. So it's just pretty bad timing.

CHANG: Right.

SECAIRA: Officials throughout Northern California have told me they're advising people to hold off on fireworks in red-flag areas tomorrow since most fires are human-caused, and, you know, that makes it a pretty reasonable concern.

CHANG: Yeah. Well, as we've been mentioning, this heat obviously can be very dangerous. How are officials trying to keep residents safe this summer?

SECAIRA: Right. And it's interesting. Heat is a leading cause of weather-related death. And usually during extreme heat, we're worried about older adults, children, pregnant people. But right now, officials are telling me that it's not just more sensitive populations that could be impacted. It's anyone who's working outside for extended periods of time, anyone spending a lot of time outdoors. So we're seeing cooling centers open up throughout the state, which are places equipped with AC where people can get shelter. And then there's also volunteer efforts I've seen where people are passing out water bottles to unhoused people who are just really in danger during heat waves.

CHANG: That is Manola Secaira with CapRadio. Thank you so much, Manola.

SECAIRA: Yeah, thanks for having me. Transcript provided by NPR, Copyright NPR.

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