An extraordinary heat wave toppled records this week across the Western United States. In California, it brought the hottest temperatures ever recorded in March.
The final days of winter felt like summer, and across the state, many have wondered what it means for actual summer. If the temperature in Death Valley soared to a record-breaking 104 degrees in the middle of March, would it rise even higher in July?
No one can say for sure in March what the temperature will be in July. Meteorologists can create seasonal forecasts that look several months into the future and estimate whether temperatures will be above or below normal, but those forecasts are not precise. They can’t reliably forecast specific weather beyond seven or 10 days.
But while this heat wave doesn’t dictate California’s summer temperatures, its effects will linger in other ways into the months to come. Here are three of them.
A critical water source is disappearing more quickly.
The snow in the Sierra Nevada was already thin after an unusually warm and dry winter, and the heat wave has threatened what little remained.
Over half of the dozens of stations that measure snow across the mountain range are reporting levels there are well below normal.
The snow that piles up in the Sierra every winter provides a buffer during California’s dry, hot season. Because California gets nearly all of its annual precipitation in the winter, the snowpack acts as a frozen reservoir, providing as much as a third of the water the state uses for drinking, industry and agriculture. Its runoff provides water to trees and vegetation in the spring and summer.
The snowpack usually starts to melt around April 1. This year, that process began early, after a warm storm in late February brought rain instead of snow to the highest peaks of the Sierra and wiped out the snow at elevations below 6,500 feet, said Anne Nolin, a professor in the department of geography at the University of Nevada, Reno.
The heat this week is speeding the melt even more.
“This heat wave is going to really decimate the remaining snowpack,” Dr. Nolin said.
The California Department of Water Resources said 2 percent of the statewide snowpack, on average, had melted each day since Monday.
Jason Ince, a spokesman for the department, called that degree of melting unusual.
Peak fire season could arrive earlier.
Wildfires in California have gone from seasonal hazards to year-round catastrophes in a changing climate. But fires are generally at their peak from June through September. This year, the landscape could be primed for fire earlier.
John Abatzoglou, a climatologist and researcher at the University of California, Merced, said this heat wave had been like a giant hair dryer sitting over the state, pulling the moisture from the soil and vegetation.
The landscape dries out every year, but the above-normal temperatures have fast-tracked that process this week.
Matt Shameson, a fire meteorologist with the U.S. Forest Service in Southern California, said that in a typical year, the grass is fully cured — dead and turned brown — by mid-May. This year he expects that to happen by mid-April.
“Once the grasses are fully cured, we’ll start to get grass fires, but we’re not there yet,” Mr. Shameson said. “We’re getting some small fires but no significant ones.”
Heavy spring rain could wet the landscape again and bring snow to the mountains, lessening the fire threat. Weather models point to a potential chance for rain in California at the end of March and the beginning of April. But storms in the spring tend to be weaker and less frequent than in winter and are not likely to have as significant an impact. Mr. Shameson said that even if the state received two to three inches of rain in the coming weeks, it would not stop the grass from turning brown.
“Once the grasses start to die, they don’t come back,” he said. “That process has started.”
Drought conditions are likely to return.
California has been free of widespread extreme drought for a few years, and in January, it was completely free of drought for the first time in decades, thanks to back-to-back storms in December, but that may not have been enough.
Drought is creeping back into the state, and the melting snow, the unusually warm winter and the heat wave are all to blame.
Localized areas have struggled with dry conditions, especially in Southern California, which suffered a dry period in 2024 and 2025. A few big storms swept the state this winter, and precipitation arrived early, but many of the storms were warm, delivering more rain than snow, a trend observed across the Western United States.
The National Oceanic and Atmospheric Administration predicts that drought conditions will be widespread across a large area of Northern California by the summer. The snowpack in this area is especially low right now, at only 16 percent of its normal levels for this time of year.
Amy Graff is a Times reporter covering weather, wildfires and earthquakes.
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