SAN FRANCISCO (CBS SF) — The latest U.S. drought data released Thursday morning shows the entire Bay Area in extreme drought conditions, as well as most of California.

Last week, portions of Alameda, San Mateo and Santa Clara counties were still at the D2 level, indicating severe drought. On Thursday, the map had all of the Bay Area at the D3 extreme drought level.

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In California, the areas of extreme drought expanded across the northern and central Sierra Nevada, as well as in areas of the San Joaquin Valley, where water deliveries have been severely reduced due to the poor snowpack conditions across the Sierra and below normal reservoir conditions, according to the U.S. Drought Monitor.

The expanding areas of extreme drought are a result of a combination of factors including back-to-back dry water years, above-normal temperatures, below-normal snowpack, and drought impacts (agricultural, ecosystem health, water supply, recreation).

Image of drought levels in California released on May 6 showing most of the state in extreme drought conditions (left), drought conditions on April 22. (U.S. Drought Monitor)

Since October 1, precipitation across most of California has been much below normal, with some locations – including the greater Bay Area and areas of southeastern California – experiencing record or near-record dryness, according to the national monitor.

In the west, 83% of the region is currently in moderate-to-exceptional drought with the most severe conditions centered on the Four Corners states, California, and Nevada.

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The extreme drought conditions mean Bay Area residents will likely see additional water restrictions on top of those already enacted.

On Tuesday, the Marin Municipal Water District Board voted unanimously to impose further restrictions on water use in the county, which is experiencing its driest period in the last 142 years.

On Monday, an advisory committee for North Bay water agencies passed a resolution asking residents to voluntarily reduce water usage by 20%, with water storage levels in Lake Mendocino and Lake Sonoma at historic lows.

Last week, the San Francisco Public Utilities Commission asked for a 10 percent voluntary reduction in use from its irrigation customers and a similar request for city departments.

Other parts of the Bay Area have already taken steps toward voluntary reduction of water use, with the East Bay MUD Board of Directors declaring a stage 1 drought for the water district and the Sonoma County Board of Supervisors approving a resolution declaring a drought emergency.

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Amid the drought conditions, California fire officials Monday issued warnings of an early and longer fire season this year. Not even halfway through 2021, the state has already had more than 1,800 wildfires, surpassing last year’s record pace.