Spring heat, a blow to RFK, Jr.’s vaccine policy, lead in kids’ clothes
March 23, 2026
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Spring heat, a blow to RFK, Jr.’s vaccine policy, lead in kids’ clothes
An unseasonal heat dome over parts of the U.S., a federal court ruling that blocks the CDC’s recent change to its recommended childhood vaccine schedule, new research on unsafe levels of lead in fast fashion
By Kendra Pierre-Louis, Andrea Thompson, Sushmita Pathak & Alex Sugiura
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Kendra Pierre-Louis: For Scientific American’s Science Quickly, I’m Kendra Pierre-Louis, in for Rachel Feltman. You’re listening to our weekly science news roundup.
If you live in much of California or the southwestern U.S., you’ve likely been muttering to yourself, “it’s hot in here.” Last week a heat dome that centered on that region but that was expected to expand as far east as Mississippi and as far north as southern Montana created unprecedented mid-March temperatures that teetered into the triple digits in some places.
To demystify this early heat wave and its links to climate change, we have Andrea Thompson, senior desk editor for life sciences here at SciAm.
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Thanks for joining us, Andrea.
Andrea Thompson: Thanks for having me.
Pierre-Louis: So spring just started, and much of, like, the Southwest and parts of the western U.S. are cooking; they’re baking. What’s going on?
Thompson: Yeah, so, you know, this is following on a, a March that has been really wild weather-wise in general. You know, March is the beginning of spring, so this is a transitional weather season anyway as the sun comes up and the jet stream over the U.S. kind of shifts. So you have warm and cold air masses colliding—you get things like tornadoes and extreme weather, which we’ve seen.
What’s happening here is: this is an area of high pressure, or a ridge in meteorology speak, and it is incredibly intense, especially for March. And when you have these ridges, temperatures just skyrocket.
So this is an incredibly huge and incredibly extreme and an incredibly persistent heat event, especially for this time of year.
Pierre-Louis: So we know with heat events, there are kind of two big problems, right? One is the heat itself—like, 100 degrees [Fahrenheit, or about 37.8 degrees Celsius] is just 100 degrees. But if you’re coming from a period where it’s maybe not been so hot and you’re now being slammed with 100 degrees, the body really struggles to adapt.
Thompson: Right, the body acclimates as temperatures gradually warm through spring, and then you get into summer. Whereas right now we’re basically plopping summer down right at the end of winter [Laughs], and bodies aren’t ready for that.
Pierre-Louis:  So there really is a risk that, you know, some people might get quite ill or even die from this heat wave.
Thompson: Yeah, there’s definitely that potential, and there are heat advisories and extreme heat warnings out in some places, you know things like that.
Pierre-Louis: This is all happening also at a time where much of the West, I believe, is dry. So what is this combination of very hot weather and already somewhat dry conditions going to do?
Thompson: A lot of the West, in particular, you know, in the Rockies, has been pretty dry this winter, and it’s been a very warm winter. In fact, western U.S. has more distinct wet and dry seasons, and they depend a lot on snowpack that builds up during the winter and gradually melts in spring and summer. But there’s not [Laughs] a lot of snowpack left already ’cause it’s been so warm, and a lot of what precipitation fell this winter fell as rain. What snowpack is left, a lot of that’s gonna get melted out by this event. And the ground and rivers may not always be able to absorb all of it, so some of that’s going to be lost.
So you’re setting up, you know, a drier spring and summer, which makes the potential for a really bad wildfire season a lot higher. The biggest wildfire in Nebraska’s history is, is happening there right now. So, you know, there’s a big concern, and especially in some of the higher mountain forests that we haven’t seen a ton of wildfire activity in the last few years, that that could change with things being so dry and the snowpack so low.
Pierre-Louis: So that naturally raises the question of climate change. Kind of how does that factor into everything that we’re seeing?
Thompson: So at the very basic, climate change means that when you have a big heat event, it’s going to be hotter than it