Extreme Weather

Are heat waves becoming more common?

October 31, 2023


Heat waves are not only happening more frequently, they are also getting more intense.

Numerous heat records were broken in June and July of 2023 with several parts of the Northern Hemisphere experiencing extreme heatwaves—southwest United States, Mexico, Southern Europe and China. Without human induced climate change, these heat events would have been extremely rare. Heat waves are now occurring more often than they did in the 1960s—about six per year now compared to two per year then—and lasting longer.

We are also seeing more heat-related deaths. Research indicates that as the climate continues to get warmer and there are more extreme heat days, the role that extreme heat plays in the cardiovascular health of adults will increase as well.

Key Takeaways

  1. 1.

    During the 2020s, the average heat wave has been 2.3°F above local thresholds for metropolitan areas included in the EPA’s indicator.

  2. 2.

    There has been an uptick in heat-related mortality.

Additional Resources

Centers for Disease Control and Prevention, Climate & Health Program: Heat & Health Tracker

American Heart Association: Projected Change in the Burden of Excess Cardiovascular Deaths Associated With Extreme Heat by Midcentury (2036–2065) in the Contiguous United States