Miami mansion boom rages on

This 8-bedroom, 16-bath Boca Raton estate is currently on the market for $35M
Douglas Elliman

Luxury real estate in Miami Beach continues to party on.

Prices for luxury homes in Miami Beach and the Barrier Islands jumped 10 percent in the second quarter and 8.7 percent compared with last year's second quarter, to an average sales price of $950,832, according to a report from Douglas Elliman Real Estate and Miller Samuel Real Estate Appraisers & Consultants.

Parts of the Miami market are showing signs of strainespecially with rising inventories. And there is a growing split between the most exclusive communities and the rest of Miami.

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The median sales price for condos in Miami Beach and Barrier Islands fell 1.1 percent in the quarter to $335,000. Yet the median price for three-bedroom and four-bedroom homes was up more than 20 percent. The median price in the luxury segment of the market (the top 10 percent) was up 7.8 percent in the quarter and 10 percent compared with the same quarter a year ago.

The hyper-exclusive communities of Bal Harbour, Fisher Island and Surfside saw big gains in average pricesbut declines in median prices, suggesting that a few big sales skewed the averages. Average sales prices for condos in Bal Harbour soared 71 percent compared with the same quarter last year, to over $2 million. Median prices were up a more moderate 19 percent year-over-year.

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Average sales prices in Bay Harbor were up 51 percent year-over-year, and they were up 51 percent in Surfside.

Yet the tide of inventories is slowing rising. Listing inventory is up 34 percent year-over-year and the absorption rate is up 60 percent over the same quarter in 2013, rising to 8.3 months. That's still low for Miami. But with so many new condos coming on to the market in the coming months, Miami's white hot market may be due for a little cooling off.

—By CNBC's Robert Frank.