One of the coldest Januarys on record was hard on humans. But it has hurt few plants and may actually benefit cherry blossoms this spring, according to the National Park Service.

No one is predicting yet whether the 1,200 cherry trees around the Tidal Basin will bloom during this year's Cherry Blossom Festival, April 2 through 4. Their blooming has concided with the festival only once in the past five years.

The Park Service's chief horticulturalist, James Lindsay, said yesterday that there should be many more blossoms and longer-lasting blossoms this spring because of the unbroken cold spell.

The abnormally warm winters the East Coast has enjoyed since 1972, with their alternating freezing and thawing weather, killed one-third or more of the early-blooming buds on fruit trees, and then cut short the brief blooming period of the remainder, said Lindsay.

The forecast of continuing cold weather is good, too, from a plant lover's point of view, says Erik Newman, a curator at the National Arboretum."It's the constant freezing and thawing that causes the ground to heave and break roots," Newman said.

Snow and ice already on the ground actually protect grass, flowers, shrubs and even trees, he said, because they act as a blanket, insulating and preventing the ground from freezing too hard.

The National Weather Service forecasts below normal temperatures at least through the weekend, with a chance of snow or rain on Friday. The average high temperature for this time of year is 44 degrees and the average low is 28, over the past 30 years.

Today, Groundhog Day, when that animal performs its mythical bit of weather forecasting, is predicted to reach a maximum of only 35 to 40 degrees. According to legend, if the groundhog (German hedgehog or French bear) emerges from its burrow and hibernation today and sees its shadow, then he will scurry back inside and neither he nor warm spring-like weather will appear for another six weeks.

Today also is Candlemas Day, the ancient feast of the Virgin Mary that also has been hailed as a harbinger of spring - "If Candlemas Day be fine and clear, we shall have winter half the year."

Both the groundhog and Candlemas legends apparently are based on the folklore that early February is a "weather-breeder, a period of change in which future weather patterns are set," says Albert Lee in his book "Weather Wisdom."

Lee and most meterologists dismiss this as as absurb as predicting the severity of a winter by the thickness of an onion's skin or caterpillar's fur.

The National Weather Service does hazard long-range predictions - with a success rate of about 60 per cent - and forecasts that February will be abnormally cold this year.

Park Service records show the past five years have all had brief and poor cherry blossom showings, with 1975 the shortest when 60-mile-per-hours winds whipped most blossoms from the trees after only two days of bloom.

Last year the blossoms around the Tidal Basin bloomed feebly for a week in late March, and the trees were bare during the festival from April 5-10. The trees bloomed after the festival in 1972, 1974 and 1975 and only during part of the festival in 1973.

Last fall more than 450 young Yoshino cherry trees were planted around the Tidal Basin, bringing the total to well over 1,200. Several thousand later-blooming Kwanzan cherries are planted around Hains Point.