The latest numbers on the Miami mansion market show it is getting frothy and probably will continue to be so through at least next year.
The median sales price in Miami rose to $240,000 in the third quarter, a 23 percent gain from the the year-earlier period, according to a report from Douglas Elliman and appraisal firm Miller Samuel. The number of sales rose 20 percent, while inventory fell 8 percent. The absorption rate, or the rate at which homes are sold, declined by 24 percent, the report said.
Mansions and ultraluxury condos are especially hot. Looking at the top 10 percent of sales, the median price for a condo is now $1.2 million, and sales are up 19 percent. The median price for single-family luxury homes jumped 16 percent, to $1.5 million.
(Read more: Hottest ZIP codes for megahome sales)
Sound like a bubble? Perhaps. Especially when you consider that a large number of Miami buyers in recent years came from Brazil and other Latin American countries no longer creating as much wealth or affluent real-estate buyers.
"The spigot from Latin America has definitely slowed," said Jay Parker, CEO of Florida Brokerage for Elliman. "We've seen a retraction in that market."
But a surge in demand from other overseas buyers and from New Yorkers—especially those in the financial community—has more than made up the difference, Parker said.
(Read more: Sales of super-pricey pads hit four-year high)
The New York contingent is no longer retirees flocking to Florida but younger, wealthy families looking for a better-quality and lower-cost lifestyle, according to Parker. Technology has also allowed more traders and bankers to work remotely.
"In our market, New York is the new Latin America," he said.
Jonathan Miller of Miller Samuel said Miami is becoming an alternative to the Hamptons, the ultraluxury resort area on New York's Long Island.
"I've never seen such a correlation between the two markets as I'm seeing now," he said. Given the Long Island traffic, "the commute time to Miami and the Hamptons [from New York] is about the same."
Brokers, however, admit that the Miami price increases will likely slow, if only because they have soared so dramatically since 2009.
(Read more: Versace mansion sale disappoints)
For example, at the Apogee South Beach, one of Miami's most expensive towers, Unit 1101, a 4,154-square-footer with prime views, went for $4.8 million in 2009. Elliman sold it recently for twice that amount.
Jorge Uribe, who is with One Sotheby's International in Miami, noted a Coral Gables home that recently sold for $9.8 million. While properties in that area have typically gone for $1,000 a square-foot, this sale hit about $1,500.
"The demand is just really hot still," Uribe said. "Especially for the bigger properties."
—By CNBC's Robert Frank. Follow him on Twitter @robtfrank.