Extreme heat: Tracking temperatures and risks across the US this summer

(CNN) — High temperatures affect public health across wide swaths of the United States each summer, causing spikes in emergency room visits and hundreds of heat-related deaths. As temperatures rise, CNN is tracking extreme heat conditions and the potential risk for Americans each day.

To help prepare Americans for the dangerous temperatures, the National Weather Service and the US Centers for Disease Control and Prevention this year released a new national forecast predicting heat-related risks.

It considers the severity and unusualness of forecast heat and its potential duration, while also factoring the likely impact on residents in specific locations based on CDC data for past effects, such as deaths.

This map shows the latest forecast.

A large slice of the American population lives in places that will be subject to heat advisories, warnings and watches from National Weather Service this summer. More than 60 million people, on average, endured such conditions from June 21 to Sept. 22, 2023, according to data released by the service.

This chart shows that population each day during the last month.

As the planet warms, heat waves are now more common, intense and long-lasting, and temperatures are warming even faster overnight — not cooling down enough to offer relief.

As those temperatures rise, heat records will also fall.

The weather service each day releases a forecast for potential record-breaking temperatures, by location, across the country. Here are places where high temperature records could be broken over the next three days.

Forecasters from the National Weather Service also try to predict average temperatures across regions of the country over the coming weeks. This map shows the chance that areas of the continental United States will be above, below or near normal average temperatures.

Darker shades represent areas where the average temperature has an increased chance of being warmer or cooler than usual. Gray areas are expected to be near normal.

Predictions often hold true, breaking daily high temperature records. This map highlights locations across the continental United States where temperatures exceeded calendar day records, according to the Southeastern Regional Climate Center.

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