The fourth quarter is invariably the slowest and weakest period of the year for the city’s housing market. Because of the holiday season, New Yorkers are more interested in shopping for gifts and taking the kids to see Santa than shopping for a new residence.

Not so this year, according to four real estate pros, all of whom tell me the New York housing scene is humming again, contrary to all the gloom and doom talk you hear and read about. They all say sales in the Big Apple are beginning to display considerably more zip despite the usual fourth quarter weakness.

One is veteran real estate broker Deanne Esses, who plies her trade as senior vice president of Bellmarc Realty. About two months ago, she was miserable, telling me at the time prices were down on practically everything, inventories were swelling, sales were slowing, and her firm was doing so poorly that a fair number of Bellmarc brokers were leaving to pursue other careers. It was as though, she told me, “the city’s real estate business had gone on a long vacation.”

Well, that vacation, according to Ms. Esses, is over — which is good news if you’re looking to sell your apartment and bad news if you’re looking to buy one.

“We had a great November, the market is getting much better, and I think housing in the city may finally be turning around,”Ms. Esses says. Part of this, she believes, might reflect sharply higher rental prices. “Rentals are getting so steep it may be cheaper to buy than to rent,” she says.

Coldwell Banker’s Elayne Riemer, who sold an East Side apartment once occupied by Mayor Giuliani, agrees. “The market is definitely healthier, and there are practically no bargains around,”she says. It’s not, she adds, that the market is going up dramatically, which it’s not, but importantly, that it has stopped going down. Ms. Riemer notes that just about everything is selling at higher prices than a year ago — from the $400,000 studio to the $5 million three-bedroom penthouses. Indicative of this, she tells me, the average sale price at Coldwell Banker is up 7.5% from last year.

One reason for the peppier housing picture, it’s widely believed, is the advent of Wall Street’s big year-end bonuses. Last year, they totaled about $21.5 billion. This year, they’re expected to run about 10% to 15% higher.

Some other positives are said to be the curtailment of new construction, limiting the available supply, the city’s improving economy and employment picture, and the weak dollar. Also, Ms. Riemer says, buyers are increasingly realizing all the housing bubble talk they’re reading about in the newspapers is hogwash.

Jonathan Miller, one of the city’s leading real estate appraisers, also confirms the housing pickup. “We’re seeing a decided increase in the number of transactions ” he says. It suggests to the president of Miller Samuel that next year’s first quarter could be a good one, especially when compared to the traditionally weak current quarter.

Mr. Miller, who conducts well-publicized quarterly surveys on the state of the city’s real estate business, also points to the upper end as one of the best performing sectors of the market, notably apartments at $3 million and up.

What about overall inventories? Including new construction, they’ve leveled off, he says, holding at about 7,600 units the last couple of months. Overall, though, that’s still higher than the average 4,000 to 5,000 units that have been on the market over the last five years.

Given his assessment, indications are prices could firm or head up a bit from the third quarter’s average prices.

“Things are definitely picking up,” Brown Harris Stevens broker Vicki Gershwin also says. She notes, for example, most of the apartments at 15 Central Park West, a luxury building under construction with views overlooking Central Park, whose prices run north of $10 million, are practically gone. She finds the upper end especially active; ditto studios and one bedrooms because of the substantial inventory of these apartments on the market.

The bottom line: With city housing humming again, if you’re a buyer, the message is clear — act sooner than later or pay more.

dandordan@aol.com