(Adds new federal grants to aid in drought relief)
By Sharon Bernstein
SACRAMENTO, Calif., July 18 (Reuters) - California's drought - its worst in decades - is likely to hold steady through the summer months and may not ease in the fall even with an anticipated El Nino weather pattern, a federal drought expert said on Friday.
Extreme drought conditions have enveloped California - the most populous U.S. state and an important agricultural center - since the beginning of the year.
The conditions have left more than 80 percent of the state in parched conditions defined as "extreme" as of this week, up from about a quarter at the start of 2014, according to the National Drought Mitigation Center, based at the University of Nebraska.
There is the prospect of relief this fall in the form of rains that typically occur when equatorial ocean temperatures rise in a condition known as El Nino, but the latest predictions indicate that the El Nino effects will be moderate to weak.
"Usually a strong El Nino will bring strong rains, but the weaker ones not so much," said David Miskus, a meteorologist and drought expert with the U.S. government's Climate Prediction Center. "Right now, they don't think it's going to be a strong El Nino."
The state is struggling through its driest year since 1977, according to this week's report on drought conditions authored by Miskus and released by the National Drought Mitigation Center.
California is in its third year of a devastating drought that is expected to cost its economy $2.2 billion in lost crops, jobs and other damage. The drought has forced ranchers to sell cattle for lack of grazing land, and farmers to let an estimated 400,000 acres normally devoted to crops go fallow.
Federal agriculture officials announced on Friday they would provide $9.7 million in aid to rural California communities at risk of running out of drinking water in the drought, including a plan to connect residents reliant on wells in the small community of Cameron Creek Colony to a local water system.
According to the drought report, a weekly analysis of conditions provided by universities and federal experts via the Drought Mitigation Center, about 82 percent of California is considered to be in conditions of extreme drought, and 36 percent of the state is in what climatologists call exceptional drought, the worst category.
Miskus said drought experts this week added parts of the city of Riverside and the mountains east of San Diego to the category of exceptional drought. (Reporting by Sharon Bernstein; Editing by Will Dunham)