Guiomar Aguirre, awkwardly shoving a huge package containing Christmas presents for her relatives in Miami, had been inching along in line for 20 minutes yesterday at the main District of Columbia Post Office and was still only halfway to the window.

"We do this every year," she said. "That's what happens when you work."

Maybe more people are working, or they have more money in their pockets and can afford the price of procrastination. Perhaps it is the unseasonable weather. But whatever the reason, Washington area postal officials report that postal patrons are later than usual in mailing their gifts this season.

"I'm surprised to see so many people here today," said window supervisor John Brown. "Usually the bulk of it is gone by now."

The result, Brown and others said, is a significant and unexpected increase in the volume of relatively high-cost priority and express mail pouring into area post offices, a torrent that at times this past week strained facilities that over the years have become accustomed to the Christmas rush. Customers who have waited to mail their cards and packages will be forced to pay a premium to get delivery by Christmas. Nonetheless, area postal service officials reported that they are staying "current," which is in-house parlance for keeping one's head above the letters and packages.

But in Northern Virginia, at least, it has taken some scurrying to keep "current." Thus, officials at the main Northern Virginia distribution center in Fairfax County have had to divert priority mail packages to Baltimore-Washington International and Dulles airports because their normal outlet at National Airport was simply overwhelmed.

"Priority mail is running at least 30 percent ahead of last year," said Cap Neilson, acting director of mail processing at the huge facility that handles mail for the Northern Virginia area. "It's been a heavier Christmas than usual. Perhaps the economy is a little better and people are more into it than usual."

The 1,200 workers at the plant hit a milestone last Monday, canceling 2.1 million pieces of mail at a facility that normally handles about 700,000 pieces. But the cards and packages are still coming, forcing officials to put sorters and handlers on mandatory 12-hour shifts this weekend.

Elsewhere in the area, the Christmas mail flow seemed closer to normal, although officials in Maryland and the District reported unusual volumes of priority mail.

At the Prince George's County processing plant, which handles mail from Montgomery, Prince George's, Charles, Calvert and St. Mary's counties, as well as some from Anne Arundel and Howard counties, express mail letters and packages had soared "10 to 15 percent, conservatively," said Buddy Hampton, coordinator of the service improvement team.

Hampton's theory is that much of that extra load is "pay backs. You send out 20 cards and get back 25 and there are five people not on your mailing list. So you say, 'Whoops, I'd better get those cards out.' "

In Prince George's, the flood crested last Monday, when 1.3 million pieces of mail were sorted from bins brimming with red and green envelopes and sent on their way. With the help of two new automatic sorters, the Prince George's facility has had to rely less on workers doing overtime this year, said Donald Milstead, director of mail processing.

Still, it is hardly a slow season. "Today's my day off and I came in at 4 a.m.," said Ken Robeson, an express mail and parcel clerk who has been working 72-hour weeks for three weeks. "We try to get all those parcels delivered because that could be some kid's teddy bear in there."

In D.C., mail has been running about 500,000 pieces a day ahead of last year, the expected yearly increase, and the 3,600 employes at the Main Post Office have been working relatively little overtime.

The surge in priority mail, public affairs officer George Conrad figured, is the result of more people procrastinating, and he said that could be caused by warmer-than-usual weather. "Personally, it just doesn't feel like this time of year to me."

But it's still not too late, Conrad said. Express mail dropped off by 5 p.m. Monday will be delivered on Christmas Day.