Ready for the rainy season? Here’s how La Niña is influencing the autumn weather outlook

Washington state could be looking at an abnormally wet autumn season because of an emerging La Niña weather pattern, according to forecasts from the National Oceanic and Atmospheric Administration’s Climate Prediction Center.

An outlook for September-October-November released Aug. 15 calls for a greater than normal chance for precipitation, along with an equal chance of normal temperatures through fall.

There’s a 66% chance of a La Niña forming in next few months and a 74% chance of a La Niña lasting into 2025, according to an Aug. 8 report from the Climate Prediction Center.

La Niña refers to cooling of Pacific Ocean surface temperatures along the equator west of South America.

Those changes in water temperature affect tropical rainfall patterns that in turn influence weather systems across the globe.

In the Northwest, including Bellingham, a La Niña year often means more precipitation and colder temperatures, offering a greater chance of snowfall — including both in the mountains and lowlands of Whatcom County.

Heavy rain during La Niña years has been blamed for severe flooding in communities along the Nooksack River and elsewhere in Washington state.

Flooding from a relentless series of atmospheric rivers caused an estimated $1 billion in damage across Washington and Oregon in 2021, including more than $150 million in Whatcom County.