La Niña, an ocean temperature pattern that occurs in the Pacific, is likely to continue this winter and spring, impacting weather trends across the U.S.

La Niña happens when there are below-average sea surface temperatures in the Pacific Ocean near the coast of South America.

La Niña forms when trade winds are stronger than usual over the Pacific. Typically east-to-west trade winds push warm water toward Asia.

Some years, the trade winds are so strong that they push the warm water to the western Pacific, and deep, cold water rises to the surface of the Pacific off of South America. The temperatures near the surface of the ocean interact with the atmosphere, affecting weather patterns in the U.S.

Below is a graphic showing the typical winter patterns during La Niña. Usually La Niña brings wetter and colder than average weather conditions to the Pacific Northwest and northern U.S. This will likely mean more snow chances for Oregon, Washington and the Northern Rockies.

Sometimes this pattern can also help bring average to above-average snowfall to Colorado’s northern mountains.

The opposite impact is expected across the southern U.S. where drier and warmer than average conditions are expected. This could mean less snow for the southern mountains of Colorado as well as New Mexico.

The typical weather patterns associated with La Niña correlate almost exactly with the Climate Prediction Center’s 3 month outlook for November, December and January.

The outlook shows wetter-than-average conditions for the northwest and drier than average weather across the south.

The outlook for temperature shows warmer than average temperatures are likely for everyone except the far northern states.