If you like a lot of froth with your real estate, you will enjoy the federal government's latest numbers on home-price appreciation.

But if you have been expecting the boom to fizzle any day now, and you're convinced that double-digit appreciation rates just can't keep going, you need to push back your bubble-bust timeline.

That's the upshot of the latest quarterly data on 265 major real estate markets compiled by the Office of Federal Housing Enterprise Oversight, which tracks home pricing changes nationwide. From the first quarter of 2004 through the same period this year, the average home in the United States appreciated by a near-record 12.5 percent. Some local markets were as hot or hotter in the 12-month survey period than at any time in decades.

California, which is noted for its already high real estate costs, saw an average gain per house of 25.4 percent. That is a stunning jump of close to 2 percent per month, often on homes already priced in the million-dollar-and-up bracket.

Nevada houses, though nowhere near as expensive as those in California, gained an extraordinary 31.2 percent on average during the 12 months, according to OFHEO. Three other states -- Maryland (20.97 percent), Florida (21.4 percent) and Hawaii (24.4 percent) -- saw home values gain by more than 20 percent on average. The District, treated for statistical purposes as a state, had an average gain of 22.21 percent. Prices rose 18.57 percent in Virginia.

A near-record 43 metropolitan areas had average appreciation rates at or above 20 percent, and six -- Bakersfield, Salinas and Visalia in California, Las Vegas and Reno in Nevada and Palm Bay-Melbourne in Florida -- topped 30 percent. None of the 265 metropolitan areas in the federal study experienced annual declines in values, and no state had a rate of gain lower than the national consumer price index inflation rate of 3.1 percent during the year.

But not all the signals were positive. In fact, there are distinct hints that some of the zestiest markets may already be seeing slowdowns. For example, of the top 20 metropolitan high-gainers, not one had an annualized quarterly rate that equaled or exceeded its appreciation rate for the year.

To illustrate: California's price inflation rate during the first quarter of 2005 was 3.8 percent. Annualized -- that is, multiplied by four -- that comes to a rate of 15.2 percent. That is still frothy, but nowhere as wild as the state's 25.4 percent rate from the first quarter of 2004 through first quarter 2005. That means there were previous quarters in the year when prices climbed more steeply than in the latest one.

Rhode Island had a 1.91 percent average gain in the first quarter of 2005. Annualized, that comes to 7.64 percent. Contrast that with the state's 17.1 percent average gain for the 12 months covered by the OFHEO study.

Similar shifts can be seen in dozens of other areas. A few, in fact, appear to be heading into negative territory. Beaumont-Port Arthur in Texas had a 5.2 percent average appreciation rate over the 12-month period. Yet the first-quarter annualized rate was an 8.6 percent decline. Syracuse, N.Y., posted a 12-month rate of 6.8 percent, but its annualized first-quarter rate was a 3.5 percent decline.

What to make of all this?

OFHEO's chief economist, Patrick Lawler, sees a "potential for declines in some areas" in the latest survey data, especially where there have been exceptional run-ups. The chief economist for the National Association of Home Builders, David Seiders, agrees. In fact, so do most mortgage and real estate economists, whose common refrain was summed up by Seiders last week: "This is not sustainable, not at the levels we've been seeing."

But Seiders and others are quick to point out that in wide swaths of the country -- the Midwest and South-Central states in particular -- real estate fever is not an issue. Housing values in dozens of markets in those regions continue to appreciate steadily in the mid-to-low single digits, much as they have for decades. Losing money by buying a house now at what could be the top of the cycle is not a concern.

Buyers in the supercharged markets along the Atlantic and Pacific coasts, on the other hand, would be foolish not to ask the key questions: Where are we in the cycle here? How many more quarterly reports with 20 percent gains can we really expect? Can local employment and income growth support price rises that steadily squeeze larger numbers of potential buyers out of the game?

Nobody in the federal government has the answer for you. Federal Reserve Chairman Alan Greenspan would be the first to admit it. But high-double-digit gains historically never have continued in any market for extended periods of years. They burn themselves out, slow down, deflate, correct, and yes, sometimes lose money for the last buyers onboard.

OFHEO's House Price Index data covering 265 markets can be viewed at www.ofheo.gov.

Kenneth R. Harney's e-mail address is KenHarney@earthlink.net.