Sacramento temperature blanket 2024: It’s atmospheric river season!

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It’s the busy season for California atmospheric rivers! Experts say the state’s wet season generally begins sometimes in October and sticks around until May. But peak precipitation starts right about now, in December, and lasts until February. 

These storms are a key part of replenishing California’s water supply. 

“California typically sees five strong atmospheric river storms during the winter season, and that accounts for about 30 to 50% of our annual precipitation,” said Idamis Shoemaker, a meteorologist with the National Weather Service in Sacramento.

At the moment, she says we’re in a break period, meaning no atmospheric rivers are expected to come within the next week. She says forecasters can typically predict an atmospheric river storm around seven to 10 days in advance. 

We’re seeing chillier temperatures alongside the start of this peak storm season. In November, our temperature blanket saw the return of colors last seen at the beginning of the year: Blue, which represents weekly temperature averages in the fifties, and purple, which represents weekly averages in the forties. 

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Aside from replenishing our water supply, storms that come this time of year also bring necessary water to California’s ecosystems. But levees built in the 1900s disrupted natural flooding in the Sacramento Valley.  

David Guy, president of the Northern California Water Association, says water managers have started working to reconnect wintertime rainfall with local ecosystems in recent years. That can look like pumping water into areas that historically would have naturally flooded or passively redirecting water from overflowing rivers via infrastructure that doesn’t prevent that flow, like weirs. 

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This work not only helps out wildlife but can also help sustain Sacramento Valley farmland, like its rice fields. (Fun fact: The region grows most of our nation’s sushi rice and even exports it to other countries, including South Korea and Japan).  

“We're basically trying to do 21st century water management that mimics what historically would have happened in the 19th century,” Guy says. “Scientists think that we’ll be able to mimic this in a way that will help fish and wildlife recover.” 

The November storm provided a nice start to our water supply. Guy says water managers are hopeful the trend will continue and hopefully put us in a good place when hot months return next year.