As El Niño returns in 2026, it’s important to understand this phenomenon, including how it occurs, its influence on weather throughout the United States, and the specific regions it affects most.

Temperatures across the globe have been increasing, leading to more extreme weather events, higher daytime and nighttime temperatures, and more widespread and longer-lasting heat waves. Learn more about the dangers posed by rising temperatures and extreme heat in this article, the first in our upcoming series on extreme heat.