Forecasters say 90% chance of very strong El Niño this winter, with near 70% chance of record event

The National Weather Service’s Climate Prediction Center (CPC) released its latest seasonal weather outlook Thursday, reaffirming an ongoing strengthening of El Niño heading into this winter.

The eastern Pacific tropical waters west of Peru have warmed to more than 2 degrees Celsius or about 3.5 to 4 degrees Fahrenheit above average. This warming is the result of weaker-than-normal easterly trade winds across the Pacific.

El Niño sea surface temperature forecast guidance from around the world all indicate El Niño will strengthen further through the end of the year. In an El Niño Advisory statement from the CPC, there is a greater than 90% chance of a very strong event by the end of this year, and a near 70% chance this El Niño will be a record event, with records going back to 1950.

The just-released seasonal weather outlook reflects a strong El Niño episode through this winter. During El Niño, the Pacific storm track spends more time moving into California and across the southern tier of the nation. As a result, the Pacific Northwest usually has a warmer-than-average winter with a slight edge toward drier-than-average conditions.

Impacts of El Niño

The latest seasonal weather outlook indicates that kind of a more southern winter season storm track, leaving the Pacific Northwest with good odds of warmer-than-average temperatures and no real trend in precipitation through this winter. The 3-month winter period of December through February shows a 60% to 70% chance of warmer-than-average temperatures — about as high as it’s ever been for such a seasonal weather outlook.

The outlook for this fall from October into December also reflects a similar picture with solid odds of warmer-than-average temperatures and no trend for precipitation.

Given the warmer fall and winter weather outlook, the season implies another below-average mountain snowpack, not good news for skiers and water managers. Another subpar mountain snowpack would make that 5 years in a row, leaving more limited water supplies for agriculture, fish, electric power generation, and drinking water, and the likelihood of another active wildfire season next year.

The term El Niño often generates unpleasant connotations. There are three types of conditions in the eastern Pacific tropical waters: La Niña, Neutral, and El Niño. Of the three, El Niño tends to bring the least hazardous winter weather to the Pacific Northwest.

La Niña is when those same eastern Pacific tropical waters are cooler than average, and neutral conditions are close to average.

When it comes to hazardous fall and winter weather in the Pacific Northwest — flooding, strong damaging wind storms, and lowland snow and ice, El Niño ranks last compared to La Niña and Neutral. That does not mean these hazardous weather events do not occur. They just occur less frequently. In fact, of Seattle’s top 10 snowiest winters, three of them have been during El Niño winter seasons while the rest have been La Niña seasons.

Prepare now

Regardless, now is the time to prepare for whatever hazardous fall and winter weather lies ahead. September is National Preparedness Month, a great opportunity to get ready.

Visit ready.gov or your local county or city emergency management websites for helpful readiness information for your home, car, business, and pets.

Again, now is a good time to get ready, particularly while needed supplies are readily available from retailers.

Ted Buehner is the KIRO Newsradio meteorologist. Follow him on X and Bluesky. Read more of his stories here.