Sandy Huffaker for The New York Times

In Park Place, a condominium tower in San Diego, the monthly rent on a one-bedroom unit is far cheaper than the typical mortgage payment.

REAL

For the first time since the residential real estate marathon began 13 years ago, parts of the country are showing signs of exhaustion. But if you rely on the experts to declare that a particular area's bubble has popped, you may have waited too long.

So how can a homeowner tell if a market is about to go bust? This may be one of those rare occasions when professionals parsing data are at a disadvantage to regular people watching the market. That's because the main driver of today's market is consumer psychology. Home prices go up as long as people expect them to go up.

When they stop believing, prices fall - and no economist in Washington can get wind of that faster than someone chatting over knockwurst at a neighborhood block party. "Economists looking at the macrodata will be the last to know," said Richard A. Brown, chief economist at the Federal Deposit Insurance Corporation.

What you will learn from the professionals who are dutifully crunching numbers is that prices are not falling significantly in any of the hot markets, but in a dozen or so cities in the Northeast and in California, they are near the peak. In Boston, for example, the time that homes are sitting on the market has stretched to 46 days from 39 days a year ago.

An analysis of price appreciation, done for The New York Times by the Joint Center for Housing Studies at Harvard, shows that the price appreciation in cities including New York City; Austin, Tex.; Philadelphia; and Providence, R.I., are decelerating. Appreciation in Detroit and Denver has already slowed to a crawl.

"It's taking a lot longer to sell a home," says Karl A. Martone, a Re/Max Properties agent in Providence, where homes now sit on the market an average of 65 days, up from 14 days a year ago. The region has almost six months of inventory, which is up 35 percent from a year ago.

Vicki Doran, a real estate agent with Coldwell Banker in Providence, says: "It's switching to a buyer's market. Last year buyers had to snap things up. Now they can shop around."

Even a few markets in hard-charging California - San Diego, Orange County and Santa Cruz - are part of the trend, according to data from the first three months of the year. Data for the second quarter to be released by the government on Sept. 1 may confirm the trend. But already Christopher Thornberg, senior forecaster at UCLA Anderson Forecast, a service of the University of California, Los Angeles, says California has "peaked and is already coming down the back side."

On Tuesday, David A. Lereah, the chief economist at the National Association of Realtors, said that the housing market was "probably close to a peak right now."

Take a look at the hot San Diego condo market. In Park Place, one of the many sleek towers of condominiums recently slung up around Petco Park, a one-bedroom condo is offered for $719,000. Someone buying it would expect to make mortgage payments of about $3,775 a month, plus monthly maintenance fees.

But someone really wanting to live in the high-rise, with hardwood floors, granite countertops and city views for a lot less, could rent a nearly identical unit in the same building for $2,400 a month. That is clear evidence prices have to move down. You are more apt to see that the price of residential property no longer is connected to its underlying value than a person looking only at spreadsheets of sales data.

Prices in overheated markets must, by definition, come back down to the mean. Knowing which way the market is headed before buying or selling is extremely important to anyone who wants to protect the wealth tied up in a house. And it certainly matters to anyone who is thinking of buying because it never makes much sense to buy at the top of the market. "The turning point is pretty important," Mr. Brown said, "because the trend will play out for years."

The trouble is, economists have been wrong before when they try to call the market. Three years ago, Dean Baker, co-director of the Center for Economic and Policy Research in Washington, said that it would be only a matter of months before prices began to fall. Prognosticators at the research firm Economy.com declared that the peak was last summer. Celia Chen, the firm's director for housing economics, is now saying that it will come this year.

"The timing is always difficult with these things," admits Ian Morris, chief United States economist at HSBC Securities U.S.A., who made the same call, repeatedly.