California is entering the dry season with its water resources in a precarious position, having seen its driest start to the year on record. A heat wave last week sent temperatures soaring into the 90s and even triple-digits in some locations, as the paltry Sierra Nevada snowpack shrunk even further.

Why it matters: Water and wildfire woes lie ahead for the nation’s most populous state, as spring runoff into reservoirs slows to a trickle, and forests dry out unusually early in the year.

Context: While some mountain snow and valley rain is likely during the next two weeks, it will not be sufficient to pull the Golden State out of this particularly deep rut — which itself is happening in the context of a longer-term, climate-change related megadrought.

Threat level: The most recent snow survey, conducted April 1 by the state’s Department of Water Resources, found the snow depth at Phillips Station, near Lake Tahoe, was a meager 2.5 inches, with a snow water equivalent of one inch.

• This was 4% of average for the date, the department reported, and statewide the snowpack was just 38% of average on April 1, and has further declined since.
• Typically, the snow would be at its seasonal peak at this location on April 1, with about 5 feet on the ground.

The intrigue: The paltry snow cover is particularly cruel right now since the wet season started out with blockbuster snowstorms in December, which raised hopes for some drought recovery.

How it works: California relies on its mountain snow cover to provide about 30% of its water supplies, with runoff flowing into rivers and reservoirs throughout the warm season.

• The third-straight year of exceptionally below average snowfall means that there is a greater likelihood of water restrictions. “Water conservation will remain our best tool in the face of this ongoing drought and the statewide impacts of a warming climate,” stated DWR Director Karla Nemeth, in a statement.
• “All Californians must focus on conserving water now,” Nemeth said.
• The dry conditions portend another potentially devastating wildfire season as well. Already, the National Weather Service’s Sacramento office had to issue its earliest-ever red flag warning, at a time of year when it typically issues advisories for heavy snow.
• Wildfires in California and other western states have been getting more frequent and severe as the climate has grown hotter and drier overall. In California, for example, only two of the top 20 largest wildfires in state history occurred prior to the year 2000.

The big picture: While California has seen its driest January through March period on record by far, drought currently covers a record extent across the West, according to data released last week by the National Oceanic and Atmospheric Administration (NOAA).

• The California drought is occurring in the midst of a broader Southwestern "megadrought" that a recent study pegged as the most severe in at least 1,200 years. The study, coupled with conclusions from previous findings published in 2020, found that human emissions of greenhouse gases account for about 42% of the drought's severity.
• Part of the reason for the megadrought is that climate change is leading to hotter droughts, which in turn exacerbate the drier conditions.

What’s next: It’s likely that some rain and mountain snow will fall in California during the next two weeks, as a series of weather systems swings through parts of the state. But none of these will be blockbuster storms, and it’s simply far too late to make up for the precipitation shortfall.

Go deeper: Extreme weather whiplash hits California with record heat and wildfires

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