Severity of state’s drought lessens greatly

California’s drought situation is looking better this year compared with the same time last year.

In November 2021, more than 80% of California was in extreme or worse drought, compared with about 43% this year, U.S. Drought Monitor data shows. The data is updated weekly and shows drought conditions across the country.

Aside from the San Joaquin Valley, exceptional drought conditions have been stomped out across the majority of the state. This means East Bay and North Bay cities such as Oakland, Napa and Walnut Creek are finally out of this most severe drought designation.

The California coast has also seen significant improvements this year. San Francisco, Los Angeles and the Big Sur coastline dropped from the “extreme” to “severe” category quickly after recent rains. “A wet week for much of the West helped to put a boost into the start of the current water year

after a slow start,” the drought monitor’s current summary shows.

In recent years La Niña weather patterns stomped out early season storms approaching California, but this year has been different.

Toward the end of September, the state saw a solid fall showing when a rainstorm drenched the Bay Area and Sierra. October wound up being dominated by fog that replenished the redwoods and other flora along the Santa Cruz Mountains. And November saw a weak atmospheric river churn rain and snow showers into all corners of the Southern Cascades, the Tahoe area along the Sierra Nevada, San Bernardino Mountains and the coastal mountains along Highway 1. The Bay Area also saw several rounds of showers just this past week, bringing up to an inch of rain to downtown San Francisco and close to 2 inches of rain in the East Bay hills and North Bay valleys.

Last year’s wet season — the rainier months from fall to spring — began with a bang, with a series of atmospheric rivers inspiring hope for the end of the multi-year drought. However, it ended in disappointment with scant rainfall in the new year.

This year’s sudden improvements were no fluke — they were largely driven by a global weather pattern floating thousands of miles away in the Arctic. This pattern is called the Pacific North American oscillation — or PNA. It’s marked by two phases: positive and negative.

In a positive PNA phase, a high-pressure system stalls off the coast of California and shuts our storm door. Systems that bring rain and snow are booted out and the state stays dry. In a negative phase, a low-pressure system sets up off the coast and keeps the storm door wide open. California sees storm after storm when the pattern is negative, which has been dominating since September.

While better than last year, data released Thursday shows about 38% of the state is still in exceptional drought. Areas in the Central Valley, such as Fresno, that have experienced backto-back years of severe dry conditions are at risk of experiencing widespread crop losses and water shortages.

The gains seen in the Bay Area and Central Valley from recent storms are expected to carry over into the rest of the winter season. This wet pattern is set to likely continue, according to the Climate Prediction Center, though La Nina conditions could still limit how much precipitation makes it to California.

Jessica Christian/The Chronicle A family walks across Folsom Street as rain falls in San Francisco on Tuesday. Rain has become more frequent along the coast.