It's official: Most of Berkshire County is now in a moderate or severe drought.
The weekly report issued by the U.S. Drought Monitor on Thursday placed all but five communities in North Berkshire into one of the two categories.
Rainfall for the first half of September has been less than one-fifth of normal in the county. Since Jan. 1, as measured by the National Weather Service at Pittsfield Municipal Airport, rainfall and melted snow have been 25 percent below normal.
Carving Berkshire County into three zones, the drought monitor spared North Adams, Williamstown, Clarksburg, Hancock and New Ashford, classifying those communities as abnormally dry, a predrought category.
For the first time this year, a major portion of the county, including Pittsfield, Adams, Lanesborough, Richmond, Lenox, Stockbridge, Lee, Great Barrington and adjoining smaller towns are in a moderate drought.
Now ranked as in a severe drought are towns such as Dalton, Hinsdale, Peru, Becket, Otis, Monterey and Sandisfield — a zone that had been in the moderate category since mid-summer.
Despite a "decent chance" of showers Saturday night into Sunday, "I don't see anything on the horizon that would result in a prolonged, soaking rainfall for the next week or so," said Brian Montgomery, meteorologist at the National Weather Service in Albany, N.Y.
While the summer has been marked by relatively warm and humid conditions, he added, weak or fast-moving weather systems have produced only sparse rainfall.
According to U.S. Geological Survey measurements of stream flow along the Housatonic in Pittsfield and Great Barrington, the river is running much below normal at only 20 percent of the historical average.
So far, Adams, Cheshire and Williamstown are the only Berkshire County towns that have imposed outdoor water-usage restrictions, according to the state Department of Environmental Protection.
In Lenox, reservoir levels are down to 75 percent of normal, DPW Superintendent Sean VanDeusen reported. "We need rain," he said, or the town will have to begin discussing possible conservation measures.
The two main reservoirs serving Pittsfield are "within the normal operating range for this time of year," said the city's Commissioner of Public Utilities Bruce Collingwood.
He explained that the Cleveland Reservoir in Hinsdale and the Farnham Reservoir in Washington have "tremendous capacity, so we lag the state's situation. We're very fortunate, and we have a pristine watershed."
Collingwood said there are no plans to issue restrictions since demand is "very low" at this time of year. However, if rainfall continues to be sparse, "we'll have to keep watching more closely."
Much of Bennington County in southern Vermont remains abnormally dry, though areas to the east such as Windham County, which includes Brattleboro, are classified in the moderate drought category.
Despite the stepped-up rankings for the Berkshires, most of Massachusetts is worse off.
More than half of the Bay State is now in an extreme drought, according to Thursday's report, with intensified and more widespread water-use restrictions, crop losses, gypsy moth caterpillar incursions and the prospect of a dull fall foliage season.
More than 6.5 million people are in drought zones. In terms of land area, the Drought Monitor puts 52 percent of Massachusetts in an extreme drought, with an additional 38 percent in a severe drought.
The latest study adds portions of Franklin and Hampshire counties, just to the east of the Berkshires, into the severe drought category for the first time. Much of central and eastern Massachusetts already are in that second-highest warning zone, including the Worcester and Boston metro areas, as well as Plymouth and Bristol counties in the southeast.
The Drought Monitor, founded in 1999, is a collaboration of the National Oceanic and Atmospheric Administration, the U.S. Department of Agriculture and the University of Nebraska.
Its categories include moderate, severe, extreme and exceptional. Abnormally dry is considered a predrought condition.
Contact Clarence Fanto at 413-637-2551.