The term La Niña may be one that casual weather observers as well as aficionados hear meteorologists using from time to time, especially when breaking down long-term weather trends or providing a sneak peek at conditions expected during an upcoming winter or hurricane season. But, what exactly is La Niña? Let’s take an in-depth look.

The key to how winter in the United States may unfold often lies thousands of miles away in the open waters of the equatorial Pacific Ocean. It’s there where the roots of a climatological phenomenon known as La Niña originate and eventually help shape weather patterns worldwide.