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The U.S. experienced peak heatwaves from July 28–30, 2025, with extreme temperatures concentrated across the Central and Eastern regions and little overnight relief. The event tied or broke temperature records and drove electricity prices in regions with less renewable generation well above typical July levels. As heatwaves become more frequent and intense, they place increasing pressure on electricity demand for cooling.

This tightens available supply, requires higher-cost generation to meet demand, and heightens risks to grid reliability. The heatwave clearly demonstrated which systems perform best under pressure—those with a diverse mix of power plants.

Key Takeaways: 

• Overall, clean energy saved the grid more than $114 million during the 3-day heatwave. Wholesale electricity markets with significant wind, solar, and energy storage representation saw lower electricity prices than those without.
• Regions with high clean power penetration kept electricity prices low during the heatwave. When the heatwave hit, more expensive thermal units and imported electricity were required.
• If clean power hadn’t been online, all of ERCOT’s thermal capability would have been needed and may not have been enough to meet electricity demand.

Resource updated 7/1/2026