Washington area weather has been abnormally warm for nearly two months, but winter weather will be here for Christmas, meteorologists said.

Maple buds are swelling, forsythia bushes are blooming and the grass is as green as the Christmas trees that are for sale in every parking lot.

Daytime temperatures for December are averaging 4 1/2 degrees above normal, and last month was the sixth-hottest November on record, said National Weather Service meteorologist Cory Gatef.

Tuesday's high at National Airport was 69 degrees, and high temperatures have been in the low fifties the rest of the week, Gatef said. Normal highs and lows for the month of December are 46 and 30 degrees.

"It's been hard to get into the Christmas spirit because it's so warm," said Carolyn Smith, who was loading up her car at Potomac Mills Mall. "We're last-minute shoppers because it's so warm."

Temperatures at National have dropped below freezing only five times this fall, compared with 16 or 17 times in a typical year, Gatef said.

Since winter started yesterday, he said, "that is nastily wimpy."

The balmy weather is caused by the jet stream, the high-speed winds that blow around the world from west to east. The jet stream has been hovering abnormally far north, above the Canadian border, for most of the fall. As a result, temperatures have been frigid in the western half of the country, while the East Coast and South have been basking in the sun.

But all that is about to change. Changing weather patterns in the Pacific are expected to bring colder air to the region on Christmas Day. Forecasters said highs will be 35 degrees on Tuesday and only 28 degrees the next day. No snow is forecast for either day, except possibly in Western Maryland.

In the meantime, local plants and trees are pretty confused.

"On our pine trees, the little bud on the end of each branch is starting to swell," said Tom Smith, manager of Meadows Farms nursery in Germantown. "That new growth is not hardened {and} can get killed off {by cold weather} . . . . A lot of plants are going to lose a year's growth." But the damage is not permanent, he said.

Some evergreen plants, such as azaleas, may be suffering from thirst, despite the recent days of rain, said Claire Hardy, a horticultural technician with the Fairfax County Extension Service. "They need at least an inch of water a week until the ground is frozen," she said.

Yesterday's downpour brought rainfall in the Washington area to about 2 1/2 inches this month, which is slightly above the norm, Gatef said.

Next spring's flowers may be less impressive, Hardy warned, because some crocuses and snowdrops are blooming now, and they only bloom once a year. And many area plants are still recovering from unusually warm weather last January and February, which caused premature budding then, Smith said.

There is some good horticultural news, however. Mild winters are good for camellias, flowering shrubs from Japan that often have trouble in the Washington area, Hardy said.

This year's warmer weather seems particularly strange to Washington area residents when compared to last December, when more than a foot of snow had fallen by this time. As of Dec. 20, National Airport has had only 973 degree days (the total degrees below 65) this fall, compared with 1,407 at this time last year, said National Weather Service technician Trina Heiser. Normally, the airport averages 1,191 degree days on Dec. 20.

"It should have snowed by now," said Lisa Frase, 16, of Reston, who was sporting a summer outfit of navy blue polka-dot shorts.