S.F. streaks past Seattle in 2024 precipitation — so far
San Francisco has been giving Seattle a run for its money on the precipitation front. Since Jan. 1, nearly 18 inches of rain has accumulated in San Francisco. Meanwhile, Seattle sits at just 13 inches.
This year is unusual. San Francisco has been rainier than Seattle in just 16 of the past 50 years through mid-April. In a normal year, San Francisco trails Seattle by about 2.5 inches of precipitation on April 14.
Annually, Seattle averages 16.5 inches more rainfall than San Francisco and may still surpass San Francisco this year.
While 2024’s rainfall may seem topsy-turvy, it fits expectations with El Niño, a global climate pattern that has its biggest influence on West Coast storms from January through April.
“Typically, an El Niño will result in drier conditions in the Pacific Northwest and wetter (conditions) in California,” said meteorologist Chad Hecht of UC San Diego’s Scripps Institution of Oceanography — especially in the southern half of the state.
During El Niño, the jet stream, a ribbon of fastmoving air high in the atmosphere, tends to be stronger than normal in the subtropics, guiding storms south toward Central and Southern California.
“With that extended and more amplified southern jet stream track, the frequency of storm systems impacting our area does appear to go up,” said Lamont Bain, science and operations officer with the National Weather Service Bay Area.
Due in part to the jet stream’s strength, Los Angeles has been even wetter than Seattle or San Francisco so far this year, recording 18.8 inches of rain through mid-April, nearly double its normal amount. Four inches of that came in a single February day when an atmospheric river-fueled storm resulted in historic rainfall in parts of Southern California.
This winter brought a steady stream of weaker storms to the Bay Area — a dramatic change from the start of 2023, when San Francisco rainfall through mid-April was more than 9 inches ahead of Seattle’s. This was despite an ongoing La Niña in early 2023, which typically has the opposite effect of El Niño, resulting in drier conditions in Central and Southern California.
The large storms that hit the Bay Area last year were fueled by atmospheric rivers, which don’t necessarily align with El Niño or La Niña behavior.
“El Niño is not the perfect predictor,” Hecht said.
Since 2000, San Francisco has started the year wetter than Seattle just nine times, about once every three years.
Dry weather is likely throughout California for the next week to 10 days, marking a pause to the rainy weekend pattern that plagued the state for much of winter and early spring.
There is a slight chance for rain in the Bay Area later this month, but Bain says any precipitation will be relatively light.
“Keep in mind, during this time of year our (Bay Area) average precipitation amounts are essentially nil,” Bain said. “Even a few hundredths of an inch of rain is above normal.”
While rain becomes less frequent in May in the Bay Area, showers typically continue in the Pacific Northwest. While 56% of annual rainfall typically happens by April 14 in San Francisco, that number is only 39% for Seattle. So the Emerald City may soon reclaim its title as the unofficial capital of West Coast precipitation.