"I'm ready for summer," said Sue Newman. "I am so ready for summer."

The Fairfax City mother of two ticked off why she is so eager to bid the current season good riddance: Her Girl Scout troop's annual early-winter camp out was scrubbed, replaced by an indoor sleepover. The students at her son's preschool have been cooped up inside for the past three months, unable to get outdoors and run. And perhaps worst of all: "We didn't even put up the Christmas lights this year because it was too damn cold."

For people like Newman, this winter has had all the charm of a low-grade fever. Like a lingering illness, it has hovered in the background, bearable -- barely -- but capable of instantly flaring up into something more serious, as it did Friday.

The season has had its benefits, too: filling depleted reservoirs, boosting snow-dependent businesses, improving conditions for some animals and delighting those who revel in a "real" winter.

What's more, meteorologists point out, despite the frigid conditions and the lashings of snow, this winter hasn't been the Siberian freezefest some folks say it has. Jim Travers of the National Weather Service in Chantilly called this season "a return to a more typical winter than we've had for a couple of years."

Laurence S. Kalkstein said he understands how the return of winter after a long absence can be as welcome as an icy snowball in the face. The University of Delaware professor is a bioclimatologist who studies the relationship between weather and living organisms. The biggest impact a winter like this has on people, he said, is to spawn an explosion of complaining.

He's not immune. Currently on sabbatical in Florida, Kalkstein visited the Washington area recently on business. "I didn't get sick. I didn't die. I didn't alter my plans. But I was brutally uncomfortable walking from the Silver Spring Metro to the National Weather Service building."

He was, he said, "unclimatized. When we hit the unusual, no matter what it is, that is what affects us greatly."

This winter has been unusual only when compared with recent winters. With an average Washington temperature in December and January of 34.1 degrees, and 18.2 inches of snowfall, it's been a frigid successor to last year. In 2001-02, the average winter temperature was 43.2 degrees, about 6 degrees above normal. Only 3.2 inches of snow fell, more than 10 inches below average.

What caused this winter anyway, the coldest since 1994? Meteorology is one of the most complex sciences, so forecasters can't pinpoint a single factor. Most agree, however, that it can't be blamed solely on El Nin~o, the patch of warm water in the equatorial Pacific off the coast of South America.

El Nin~o has been weak this year, just strong enough to help produce precipitation in the mid-Atlantic but not strong enough to overpower a little-understood phenomenon that had greater influence on the weather: the North Atlantic Oscillation.

The North Atlantic Oscillation is an interplay of high and low pressure systems in the Atlantic Ocean. Its impact has been obvious to any Washingtonian who left home without his or her gloves: freezing air barreling down from Canada.

On the plus side this winter, thanks to ample rain and snow, the reservoirs that serve the Washington area -- in the upper Potomac, Patuxent and Occoquan rivers -- are in good shape. Groundwater has been replenished, which is good news for people who depend on wells. Baltimore's reservoir is only about two-thirds full, though, and farmers there will need rain when they plant in the spring.

Garden plants have fared well, protected from drying winds under a blanket of snow. But some plants intended for warmer climates, such as camellias, fothergilla and hybrid tea roses, might die or suffer damage. And some early-flowering trees, such as magnolias, might not look as showy, experts predict.

"My take on the kind of weather that we have had lately is that it is not going to be as damaging as a lot of people think," said Scott Aker, National Arboretum horticulturist. "It's been consistently cold, which from a plant's standpoint is a lot better than a lot of wild fluctuations."

Aker said lawns are protected from the cold because they are dormant, though he warned that walking frequently across frozen grass can cause damage.

Like plants, most animals have taken the winter in stride. The high water levels are good for migratory fish such as shad, river herring and striped bass, said biologist Jim Cummins of the Interstate Commission on the Potomac River Basin.

The region's birds and animals are built to adapt to swings in temperature, naturalists say.

"We are not going to see a silent spring because we have a cold winter," said Ed Clark, president of the Wildlife Center of Virginia in Waynesboro. For example, he said, the ice might kill some frogs huddled in swamp mud for the winter, but that will improve the survival odds of baby frogs born in the spring because there will be less competition for food and territory.

The biggest problem for animals is not the low temperature but the snow on the ground that makes it harder to find food. That is one reason why some people are seeing flocks of robins in their back yards -- the birds are hunting berries from holly trees or poison ivy because they cannot hunt on the ground.

If the cold persists through the month, it could pose problems for early-arriving migratory songbirds, said Craig Tufts, chief naturalist at the National Wildlife Federation.

"Some early birds such as American robins, Eastern phoebes, Eastern bluebirds and pine warblers may come back to find that food resources they depend on heavily, such as earthworms and small, flying insects, are not yet accessible if cold temperatures hold for another two to three weeks," he said.

Animal control officers report more calls this year about opossums and raccoons seeking shelter inside people's homes during storms. Animal shelters say they are receiving more reports from people worried about street cats left to fend for themselves in the snow or shivering dogs chained outdoors in neighbors' back yards.

To help canines counter the cold, the Washington Humane Society has been giving away hundreds of donated doggie sweaters -- one per dog -- at its shelter at 1201 New York Ave. NE, and the Southeast Animal Hospital, 2309 Pennsylvania Ave. SE.

People might hope that mosquitoes are being killed by the cold, but many hibernate. If the cold persists into April, it could delay the start of mosquito season, but warm weather and rain will bring back the little critters quickly, said Patricia Ferrao, an entomologist with the Maryland Department of Agriculture.

The cold's effects on humans have ranged from financial to physiological.

Most everybody is paying more for heat this winter. The average Washington Gas household will pay about $800 from November to April, nearly $200 more than last year, said utility spokesman Tim Sargeant.

Winter has been tough on people who sink into depression during the gloom that starts in December.

"For those hovering on the threshold of seasonal affective disorder, this one pushed them over into the real McCoy," said Norman E. Rosenthal, a professor of psychiatry at Georgetown University's medical school and author of "Winter Blues." "A lot of people who made it okay through the last few winters are calling for help."

Neal Owens runs a Gaithersburg company that sells "sun boxes," devices that produce artificial sunshine to treat seasonal affective disorder. He said walk-in business is up 25 percent this year. A sufferer of the disorder himself, Owens said: "I can usually squeak by with about 20 minutes of light therapy a day. I'm up to 30 and 40 minutes a day, just to get through the winter."

Area hospitals report no notable spikes in weather-related emergency room visits, but bioclimatologist Kalkstein said he expects that in a few months' time, data will prove there was another legacy of this winter: an increase in infectious diseases, "mainly because we were in confined spaces and coughing on each other."

As for the rest of the winter and into the spring, the National Weather Service's Steve Zubrick said, "it's kind of a tossup on temperature." There's an equal chance that temperatures will be above normal or below normal. Forecasters are calling for wetter-than-average weather for the rest of February, March and April. Beyond that, what the weather will be is anyone's guess.

One person who isn't complaining is Matt Madigan, coach of a group of elite rowers in the Potomac Boat Club. Even though his team has spent fewer days training on the river, he said he's enjoyed this winter -- ice, snow, cold and all. "I know that if we don't get winter now, we're not going to have any water in the summer. I think it's pretty important for us to enjoy the cold weather while we have it."

Sue Newman remains unconvinced: "I just keep thinking about the pool."

Marissa Marcellino, 16, flies over a snow jump she built near Reno Reservoir in Northwest Washington.Mark Westerfield of Annandale, a coffee cup in one hand and his dog Sevilla's leash in the other, keeps watch over a sledding hill near Gallows Road and Route 50, by Luther Jackson Middle School in Falls Church.