Home prices in Los Angeles and Orange counties were down 19.4% in February from a year earlier, among the sharpest drops in the nation, according to an index released Tuesday.

That compares with a 12.7% overall drop among 20 metropolitan areas measured by the Standard & Poor's/Case-Shiller home price index.

Las Vegas showed the most severe year-over-year decline, 22.8%, followed by Miami (21.7%), Phoenix (20.8%), the drop in Los Angeles and Orange counties, San Diego (19.2%), Tampa, Fla. (17.5%) and San Francisco (17.2%).

"There is no sign of a bottom in the numbers," said David M. Blitzer, chairman of Standard & Poor's index committee.

Charlotte, N.C., was the only metro area to show an increase, 1.5%.

The index has fallen 14.8% from its summer 2006 peak.

Yale economist Robert Shiller, one of the index's creators, said this month that home prices could fall 30% from their peak.

The Case-Shiller index compares the latest sales of detached houses with previous sales, and accounts for factors such as remodeling that might affect a house's sale price over time. It excludes foreclosures. From those data, an index score is created to show price changes.

The index has a base value of 100 for January 2000. The February 2008 20-city index was 175.94.

Median sale prices compiled by La Jolla-based DataQuick Information Systems showed comparable declines. The firm reported February median home sale prices were down 13% in Los Angeles County from a year earlier, while Orange County showed a 16% decline.

The March median home sales price for Southern California, which also includes the Inland Empire and Ventura and San Diego counties, was down 20% from its peak, to $385,000, DataQuick said this month.

peter.hong@latimes.com