What is El Niño and How Does It Affect the Weather?

A major key to shaping weather patterns worldwide is found in the tropical Pacific Ocean, far from any mainland. Known as the El Niño-Southern Oscillation, this climate phenomenon is the pattern that can create significant differences in average ocean temperatures and often plays a pivotal role in how global weather patterns unfold.

La Niña Lives! — And That’s Bad News

For two winters in a row, La Niña has steered desperately needed rain and snow storms away from the U.S. Southwest, exacerbating a decades-long drought that has shriveled reservoirs and spurred horrific wildfires.

Now, hopes that the climate pattern would relent and allow moisture to rebound next winter have suffered a serious blow.