By admin 
The snowpack that refills Folsom Lake, Lake Oroville and Lake Shasta each spring — the reservoirs that supply roughly two thirds of California’s population with water — could shrink by about 40% within 25 years. As temperatures warm, more of Northern California’s water is set to arrive as rain instead of snow, with water running downstream instead of melting slowly into reservoirs as a stable water supply.
Read more Who’s picketing? Here’s which CA state workers are — and aren’t — included in strike
It is one of a dozen projections in t, released Monday. The report estimates the state will warm to around 4 degrees by the 2050s, that heat waves will last far longer, that whiplash between drought and wet periods will be more extreme, and that wildfire smoke will kill more people in California than in any other state.
Although it is full of worrisome statistics and key findings, its creators also see it as a tool to help communities across the state better prepare for changing weather patterns in the decade to come. Helene Margolis, an epidemiologist at UC Davis who studies the intersection between public health and climate change and was the lead author for the Sacramento Valley section of the assessment, called it empowering.
“Knowledge is power. And we are empowered, each of us individually, and collectively, to take action to protect ourselves and our neighbors.”
Longer, hotter summers
Sacramento is already an average of 2 degrees warmer from climate change, according to climate communications group Climate Central, and that number will double in the coming decades. Statewide average temperatures are projected to rise 3.5 to 4.3 degrees Fahrenheit by 2050 and 6 to 8 degrees by 2100. The warming California has already seen has no precedent in the past century or in estimates reaching back a thousand years, the report says.
Heat waves are where that shows up most. Under a high-emissions path, the longest heat waves will stretch to two to three weeks by the end of the century.
The Sacramento Valley’s own regional assessment is expected to be released later this month, and Margolis shared some of its projections. Using a threshold of 102 degrees, Sacramento would average 31 extreme heat days a year in about three decades, and 46 by 2100. That end-of-century figure gets worse as you travel up the Sacramento River: 56 days in Yuba City and 87 in Redding.
Extreme heat poses a significant health burden for those unprepared or at risk. According to the report, people living without shelter make up about 0.5% of Californians but account for 13% of heat-related hospitalizations. Farmworkers, other outdoor workers, older adults and low-income renters without air conditioning also face higher risk.
“You don’t need 110-degree temperatures to actually be at risk,” she said. “People with heart disease or diabetes, young children, can suffer serious health impacts at temperatures far below,” noting that some medications, especially mental health medications, raise the risk as well.
Less snow, more extreme rain
As the climate warms, more precipitation will fall as rain instead of snow, and the reduction in snowpack in the northern Sierra could be drastic. It was just this past April when the northern Sierra snowpack was at record lows. By midcentury, April snowpack is projected to shrink about 40%. With it, the natural reserve that supplies major sources of California drinking and agricultural water reservoirs such as Shasta, Oroville and Folsom will shrink as well, offering a reduced water supply during the drier summer months.
Read more Did you know the Sacramento Public Library lends kitchenware? What you can borrow
And as more mountain precipitation falls as rain, more of it will immediately race down rivers, increasing the risk of floods in the Central Valley. About 1 in 5 Californians, roughly 7 million people, already live in areas at risk of flooding.
This winter may offer a preview of a climate to come, as one of the strongest El Niño events on record raises sea levels, and warms temperatures into winter. Seasonal models are already pointing to a wet winter across the state.
Smoke, and a longer fire season
The report’s most significant health projection involves wildfire smoke. California is expected to see more than 5,000 additional deaths a year from smoke by 2050, the biggest increase of any state.
Smoke from fires in the Sierra foothills, the North Coast and the northern Sacramento Valley often settles over Sacramento, and late-summer smoke tends to arrive during heat waves.
“It used to be that wildfires were a fall phenomenon, and now they’re basically year round,” Margolis said.
Between 2011 and 2020, the Sacramento Valley was already a hotspot for days with unsafe levels of smoke during heat as highlighted in the report. It’s a nasty combination, as higher temperatures cause people to breathe polluted air at faster rates.
A prolonged fire season, combined with longer and more intense heat waves, will lead to more health effects for the Sacramento region in the long run.
What’s next after climate assessment
The assessment will help guide state and local policy on preparing for climate change to come. However, the report arrives with little federal company. The author team for the Sixth National Climate Assessment, the country’s main review of climate risks by region, was disbanded by the Trump administration, leaving state reports like this one among the few current, government-backed reviews for climate change guidance.
Margolis remains optimistic.
“It’s not hopeless. It’s not scary. If we are prepared, we can reduce the risk to ourselves and our families.”
Read more Who’s picketing? Here’s which CA state workers are — and aren’t — included in strike
This story was originally published October 21, 2026 at 11:20 AM.