WASHINGTON (AP) – The slowdown in the nation’s long housing boom, which has been anticipated for at least two years, seems to have finally arrived.

Sales of new homes came in at the slowest pace in a year in January, and the backlog of unsold homes rose to an all-time high, the Commerce Department reported Monday.

Making those developments even more dramatic was the fact that they occurred during an exceptionally mild January – the warmest in more than 100 years.

“The weather in January was as good as it gets, yet demand fell,” said Joel Naroff, chief economist at Naroff Economic Advisors. “The decline in new home sales in January makes it clear that there is some real softening in the housing market.”

The Commerce Department reported that sales of new single-family homes dropped by 5 percent to a seasonally adjusted annual rate of 1.233 million units last month.

That was the slowest pace since January 2005 and left the number of unsold homes at a record high of 528,000.

On Wall Street, tumbling oil prices helped lift investors’ spirits. The Dow Jones industrial average rose 35.70 points to close at 11,097.55 on Monday.

The 5 percent sales decline was bigger than expected, dashing hopes that the milder-than-normal January would help to bolster demand. The warm weather had pushed up the level of construction starts last month by 14.5 percent, the fastest rate in three decades.

But the new report showed that with sales lagging, the increase in building activity left a total of 528,000 new homes still for sale at the end of the month, a nine-year high.

That represented an increase of 20.8 percent from a year ago and raised the prospect that a glut of unsold homes around the country could start driving down prices.

That didn’t occur in January, however. Even with the softening in sales, prices were up with the median price climbing to $238,100, up 4 percent from December, but below the all-time high of $243,900 set in October.

For the past few years, home prices have been surging at double-digit rates, gains that analysts said will likely slow now that sales are softening and inventories of unsold-homes are rising.

Ian Shepherdson, chief U.S. economist at High Frequency Economics, predicted “real downward pressure on prices over the next few months.”

Some economists are worried that with the inventory of unsold homes rising, there could be significant downward pressure on home prices, triggering a chain-reaction similar to the bursting of the stock market bubble in 2000, a development that contributed to the 2001 recession.

But new Federal Reserve Chairman Ben Bernanke told Congress earlier this month that for now he was looking for a moderate slowdown in the housing industry, not a crash.

David Seiders, chief economist at the National Association of Home Builders, also predicted a slowing but not a housing crash.

He said that home price gains, which predicted that home price gains, which were running around 12 percent last year, will slow to about 6 percent this year.

He said a lot of this year’s change will reflect less speculative investor activity and more sales spurred by people desiring to live in the homes. “Hopefully, that is all that is developing here,” Seiders said.

The 5 percent January drop in sales followed a revised 3.8 percent increase in December and was the biggest setback since a 7 percent drop in November.

The biggest decline in sales was a 14.9 percent decrease in sales in the Northeast, which followed an even bigger 23 percent plunge in sales in December. Sales in the Midwest were down 10.8 percent after having risen by 21.2 percent in December.

In the South, sales fell by 10.3 percent in January, following a 1.2 percent gain in December.

Bucking the national trend, sales in the West posted an 11.3 percent increase in January after a 6.3 percent gain in December.

Mortgage rates have been rising gradually with the 30-year mortgage now at 6.26 percent, according to the latest Freddie Mac survey. Many analysts believe 30-year mortgages will rise to between 6.5 percent to 7 percent by the end of this year.

They think that increase will be enough to trim sales of both new and existing homes and slow the double-digit gains in prices seen in recent years. The National Association of Realtors reported earlier this month that a record 72 metropolitan areas saw double-digit gains in home prices in the final three months of 2005 compared with price levels at the end of 2004.