California remains in the grip of a yearslong drought, but recent storms have led to some improvement, according to the U.S. Drought Monitor’s weekly report.

The latest map issued Thursday showed some contraction in all categories of drought, including “exceptional” and “extreme,” compared to a week earlier. A year ago the two worst categories combined covered most of the state.

“Hefty rainfall amounts in some of the coastal mountain ranges of California caused high streamflow, which lessened precipitation deficits and led to localized improvements,” the monitor reported. “Widespread improvements occurred in parts of the central Sierra Nevada range, where heavy snow fell and added to a healthy early-season snowpack.”

The monitor noted that some precipitation occurred close to the Tuesday morning data cutoff for the current report and more data will be available for analysis next week.

While the monitor’s report is modestly positive, early season storms can abruptly give way to a dry winter, and experts say it would take multiple years of significant precipitation to overcome deficits.

On Wednesday, the Metropolitan Water District of Southern California declared a drought emergency for all of the region, clearing the way for potential mandatory water restrictions early next year that could impact 19 million people.