At the Central Union Mission at 14th and R streets NW the hand-lettered sign went up at 6:15 last night: "We have no beds left," it said.

As temperatures have dropped well below freezing on recent days, the hard-core homeless are overflowing local shelters. The 20- to 25-degree weather that settled in last night was expected to continue for the next few nights, with accumulations of snow.

"People are coming in off the grates," said Dennis Bethea, chief of the District's Office of Emergency Shelter and Support Services. At the Pierce School Shelter in Northeast Washington, for example, 146 men sought shelter Tuesday night, compared with a nightly average of 126 last week.

"We're running over capacity every night," said Robert Rich, executive director of the Central Union Mission, which housed 73 men Tuesday night -- three over its official capacity. Unable to cope with additional overflow, mission workers took 15 men to other shelters.

"Many of the men that are on the streets prefer to stay out there," Rich said. But, he said, "When it gets very cold, they don't have much of a choice but to come in."

In the past week, more persons have asked for shelter each night "than on our coldest night last year," said the Rev. Vin Harwell of Mount Vernon Presbyterian Church, one of nine churches in the Groveton-Fort Hunt-Mount Vernon area that take turns functioning as shelters. He said the two churches used this week have been hosting an average of 50 a night, compared with 43 on the busiest night last year.

At the Bethesda Men's Shelter in Montgomery County, Manager David Hamilton put two spare mattresses on the floor and had to turn shelter seekers away.

"I had four residents of Gaithersburg come in and said they hadn't slept in a bed in more than two years," Hamilton said.

"Since the cold spell started we've been pretty much packed," said Dana Kinder of the Arlington Shelter for Homeless Men. "Nobody can stay outside in this kind of weather. They can't stay in their cars anymore."

The Community for Creative Non-Violence Shelter on Second Street NW housed 803 homeless men and women Tuesday night, compared with an average of 700 or fewer the previous week.

"That's not as many as we will see if it stays cold," predicted Mitch Snyder of the CCNV. He noted that the onset of freezing temperatures coincided with the last half of the month, when many poor people run out of money from disability or welfare checks.

At the Calvary Shelter, on Eighth Street NW, Director Terry Lynch could tell it was cold when he was approached by one 70-year-old woman who usually spends most nights in a government garage or on the Mall.

"She will only come in on the absolutely bitterest nights, and she came in last night," Lynch said. But in general, he said, "most women come in year-round." A hard-core group of between 20 and 25 homeless women here remains outside no matter what the weather, he said.

Directors of shelters for women and children and shelters that offer long-term counseling rather than emergency aid said they have found no correlation between the number of homeless people calling them and the weather.