Are we in an El Niño or La Niña year? What this winter could mean for California weather
California’s upcoming winter is forecast to be mild and drier than normal, according to experts, as climate patterns steer the state.
A reader reached out to The Bee’s service journalism team asking: Are we in for El Niño or La Niña year?, referring to weather phenomena that occurs in the Pacific Ocean and can affect weather across the globe.
A long La Niña
We’re in for another year of La Niña.
A La Niña occurs when the temperature of the sea is cooler than average in the Eastern Pacific, resulting in less evaporation, weaker storms and less moisture in the atmosphere. Its counterpart, El Niño, is when warm water moves toward the West Coast.
Paul Ullrich, professor of regional and global climate modeling at the University of California, Davis, said we’ve been in a La Niña weather pattern for two years now. This upcoming La Niña winter will be the third consecutive year. The effects of the weather pattern will vary by region, with California seeing less rainfall.
But it appears to be weakening, Ullrich said.
According to the National Centers for Environmental Prediction’s Recent Evolution, Current Status and Predictions, the La Niña will continue through the Northern Hemisphere to winter 2022 to 2023.
La Niña conditions typically span about 9 to 12 months, but can go as long as two years, according to the National Oceanic Atmospheric Administration. Ullrich said the current episode is a record La Niña in how long it has persisted.
Between La Niña and El Niño, the patterns usually switch every two to seven years.
What this means for drought?
It’s not great news for drought.
Usually a La Niña is associated with less rain overall, Ullrich said, but that’s not guaranteed. He said he expects drought to persist in Northern California.
The effect of a La Niña depends on the region. According to NOAA, a typical weather pattern during a La Niña is cool and wetter than average temperatures in the Pacific Northwest, and warmer and drier than average weather in the Southern U.S., including California and the Carolinas.
“When it comes to predicting things months out, it’s always very difficult in order to make any confident statements,” he said.
“We can still get lucky in terms of the amount of precipitation that we receive, pulling us out of drought,” Ullrich said. “But right now the odds are against us, if the La Niña persists.”
This story was originally published September 20, 2022 at 5:00 AM with the headline "Are we in an El Niño or La Niña year? What this winter could mean for California weather."