Rhode Island house prices during January, February and March fell 9.4 percent, the largest first-quarter decline in more than 20 years, according to a report released today by The Warren Group.

The median price of a single-family house fell to $240,000, compared with $265,000 during the first three months of last year, the report said.

Meanwhile, sales of single-family houses during January, February and March plunged 20.4 percent from a year earlier — the steepest first-quarter decline since 1998, data from the Boston-based real estate research firm shows.

The Rhode Island Association of Realtors is scheduled to release its own first-quarter housing numbers, including detailed city and town data, tomorrow.

Rhode Island’s real-estate slump is shaping up to be “more dramatic” than during the early 1990s, when [monthly] “double-digit drops in price weren’t the norm,” The Warren Group’s chief executive officer, Timothy Warren Jr., said in a statement. “They are now, and we’re not sure when that will end.”

Rhode Island’s median house price in March was down 10.3 percent from a year earlier. Similar house price declines were reported in Massachusetts and Connecticut.

In Massachusetts, the median price of a single-family house fell 8 percent, to $310,000, compared with $337,000 during the first quarter of last year, The Warren Group reported. Sales in the Bay State during the quarter plunged 27 percent from a year earlier, the report said.

In Connecticut, the median house price during the first quarter declined 5.8 percent, to $266,000; sales fell 27.2 percent from a year earlier, The Warren Group reported.

(The Warren Group data includes sales by owners as well as sales through real-estate agents. The numbers do not include data for the town of Barrington, because the town assessor’s reports are not available in electronic format.)

The spring and summer months are normally the busiest period for house sales, because the weather is better and people with families often prefer to move when school is out.

In March, however, Rhode Island’s single-family house sales fell nearly 18 percent, to 531 sales, compared with 646 sales in March of last year, The Warren Group reported. Condo sales in March plunged nearly 51 percent, to 98 sales, compared with 199 sales during March of last year. For January, February and March, condo sales were down 37 percent, to 315 sales, compared with 500 a year earlier.

Sales of both condos and single-family houses have fallen by double-digits every month since August, the report said.

The median condo price during the first quarter ticked down 2.8 percent, to $215,000, compared with $221,250 during the same period last year. In March, condo prices remained unchanged.

larditi@projo.com