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

CNN is tracking extreme heat conditions for Americans each day. See where the risks are greatest — and where high temperature records might be broken.

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.