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What happens when El Niño rolls into Seattle?

caption: A cyclist rides along Harbor Avenue Southwest in the rain on Thursday, November 3, 2022, in Seattle.
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A cyclist rides along Harbor Avenue Southwest in the rain on Thursday, November 3, 2022, in Seattle.
KUOW Photo/Megan Farmer

If you’re in the Pacific Northwest right now, it’s cold outside. There’s frost on the ground in the morning — sometimes a freezing mist in the air. And lately, very little rain.

Winter doesn’t technically start for another three weeks. But if this is all feeling off to you, you may need to prepare for more weirdness; it’s an El Niño year.

You’ve probably heard the term before — it’s got a sister weather pattern called La Niña. But what exactly an El Niño year means for the winter depends on where you live.

In California, for example, an El Niño year means cooler and wetter weather. In Washington, not so much.

"Our temperatures tend to be above normal for the winter, and the precipitation tends to be on the drier side," said Karin Bumbaco, Washington’s Deputy State Climatologist.

But that precipitation isn't a sure bet, Bumbaco added. It varies from year to year during an El Niño.

"What is really key though is that those warm temperatures often will cause our precipitation to fall more as rain rather than snow," she said.

That means that by April 1, we tend to have below normal snowpack, which is important for our water supply in the spring and summer.

Both El Niño and La Niña are normal weather patterns — they're the result of water temperatures off the coast of South America near the equator. During an El Niño year, that water is warmer, and during a La Niña year, the water is cooler.

But climate change may be playing a role in how warm or cold those weather patterns are.

"Our climate is warming because of climate change, but we still see changes from year to year," Bumbaco said. "But during El Niño years, since our atmosphere has a lot more warmth, we would expect that the likelihood of a record warm year is elevated."

Bumbaco said that even with the probability of less precipitation, there's always a potential for flooding in the state, and emergency managers around the state are prepared for that possibility this winter.

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