California Had Its Driest February on Record. Here’s How Bad It Was.

Not a drop of rain fell in downtown San Francisco this February. Or in Big Sur State Park. Or in Paso Robles. February in California was so dry that it is raising concerns that the state, which, according to the National Drought Mitigation Center, only fully emerged from drought last March, may be headed for another one.

“It was the driest February on record,” said Daniel Swain, a climate scientist with the Institute of the Environment and Sustainability at the University of California, Los Angeles.

Ordinarily, 90 percent of California’s rain falls during the seven-month period between Oct. 1 and April 30, with half of the state’s total precipitation falling during December, January and February. The rains that come in February are part of a seasonal pattern that nourishes plants, replenishes reservoirs and, in the Sierra Nevada mountains, restores the snowpack that provides up to 30 percent of the state’s drinking water.

But this February “was not just merely a below average month,” Dr. Swain said. “It was, in a lot of places, a completely dry month, which is truly extraordinary.”

The lack of snow and rain in February comes after a January that was also drier than average, and a record dry autumn for much of Northern California. A series of storms dumped a considerable amount of snow in late December, raising hopes that this winter might proceed normally. But that now seems less likely.

“There’s sort of this myth of the miracle March in California, which refers to a couple of specific years in which the winter was extremely dry and then March came along and there was just this unceasing deluge for a few weeks in a row,” Dr. Swain said.

In those years, the rainfall erased a large part of the water deficit. But this year has been so dry that the state would need record breaking rain and snow in the next few months to make up for the shortfall.

The United States Drought Monitor, a joint project by federal agencies, including the National Oceanic and Atmospheric Administration and the Department of Agriculture, releases drought maps weekly. They currently show much of the state as either abnormally dry or in moderate drought.

As of March 1, according to the California Department of Water Resources, the state’s snowpack was 44 percent of normal. In the Southern Sierras, the percentage was only 40 percent.

The lack of moisture is coming at a time when the state needs more water, not less. January and February weren’t just unusually dry, they were also unusually warm. On Feb. 27, for example, the temperature at the Los Angeles International Airport hit 85 degrees Fahrenheit, or about 29 Celsius, breaking a record of 83 degrees Fahrenheit that was set in 1992.

“In recent weeks there have actually been a number of days with spring or even summer-like temperatures in the 70s and 80s throughout a lot of California, which were daily record high temperatures for a portion of February,” Dr. Swain said.

The hotter temperatures, which are associated with climate change, dry out soil, making moisture less available to plants and increasing wildfire risk. The state has already seen an uptick in reported fires, according to The California Department of Forestry and Fire Protection, or CalFire, which responds to reports of wildfires.

Between Jan. 1 and March 1, the agency has “responded to 381 of those calls already,” Scott McLean, Cal Fire’s deputy chief of communications, said. Last year over the same time period, it responded to 105 reports. Over the past five years, the average number of wildfire reports during the first two months of the year was 279 calls, putting this year at roughly 35 percent above average.

It is too soon to tell what this will mean once summer hits, “but this is a group effort by everybody in the state of California to be prepared,” Mr. McLean said. The department is educating residents on fire risk, including maintaining space around their properties that firefighters can use to defend against fire, and sending out firefighters to reduce dead brush or overgrown plants that could easily ignite, as well as preparing firefighting equipment.

But increasingly, those preparations may need to take the long view. There’s growing evidence that, in a warming world, the state’s overall levels of precipitation won’t decline but the distribution of precipitation will. That is: the drier years will be drier, and the wetter years will be wetter and the state will need to find ways to cope.

“Portions of California have experienced both their driest years on record and their wettest years on record in the past 10 years,” Dr. Swain said.

And California is not the only state in the region facing these sorts of issues. The United States Drought Monitor is also showing that much of Oregon, Washington State and Nevada are also currently experiencing abnormally dry conditions.