A new investigation shows heat is even deadlier than we thought

September 4, 2026

AI Summary

5 min read

A new investigation shows heat is even deadlier than we thought

The official number from the CDC says about 1,700 people die from heat each year in the United States. But when NPR climate correspondent Alejandra Borunda teamed up with epidemiologist Quinn Adams at Boston University, their modeling suggested the real number is closer to 9,000—roughly five times higher. And even that, Borunda says, is probably still an undercount.

The problem isn't really the CDC's fault. The way causes of death are counted varies from state to state and even county to county. "This is just really hard to do," Borunda explains. The deeper issue is that heat deaths are genuinely difficult to identify and record.

Why heat deaths are so easy to miss

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What you'll learn

1 (00:20) **The Under-Counting Problem** - Host Nate Rott introduces the episode with climate correspondent Alejandra Borunda, who explains that official heat death counts are dramatically low.
2 (04:20) **A Preventable Death** - The story of Sherry Patty illustrates how heat deaths happen and why they're often avoidable.
3 (06:36) **Why Counting Heat Deaths Is So Hard** - The core structural reasons the US systematically undercounts heat mortality.
4 (08:28) **The Excess Mortality Model** - How the new estimate was calculated using statistical modeling.
5 (10:54) **Why the Estimate Is Still an Undercount** - The researchers acknowledge their 9,000 figure is conservative.
6 (11:48) **From a 'Me Problem' to a 'We Problem'** - The broader implications of the findings for public awareness and policy.
7 (13:41) **Places Doing Better** - Examples of jurisdictions that are experimenting with better tracking and protection.

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Guests on this episode

Alejandra Borunda

Show Notes

Hot weather isn’t just an inconvenience. It’s killing thousands more Americans than show up in official records. That’s the finding from a new NPR investigation, in partnership with Boston University. And the way they came up with that new, better estimate of the true toll of heat is, of course, with science. This episode, we’ll bring you all the details – and chat about why getting good estimates could save lives.

Interested in more science-based investigations? Email us your question at [email protected].

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