Fueled by consumers trying to beat an expected rise in mortgage rates, the prices of residential real estate in Manhattan soared by double-digit percentages in the first quarter of 2005 compared to the last quarter, according to a pair of reports released yesterday.

And while the astronomical rise in prices has some potential buyers wondering if they should wait for a downturn before jumping in, the experts aren’t worried. They project that Manhattan’s real estate market still has some steam left, and at worst, it may just level off for a while.

“There is a concern of rising mortgage rates, and people want to get in now before the rates go up,” said Jonathan Miller, president of Miller Samuel Incorporated, a real estate appraisal firm.

“Every paper reports it’s doom or gloom,” said the president of Prudential Douglas Elliman, Dorothy Herman. “But I don’t see the market falling out. I see it leveling out.”

The average sale price of condos and co-ops in Manhattan rose 23% during the first three months of 2005 to $1.21 million, from an average of $987,257 during the last quarter of 2004, according to the Prudential Douglas Elliman Manhattan Market Overview, released yesterday by Miller Samuel.

The median price of condos and coops rose 16.5% to $705,000, over $605,000 last quarter, the report said.

The average sales price of condos in Manhattan topped $1.5 million for the first time, with an increase of 33.9% to $1.55 million from the previous quarter’s average of $1.16 million. The median condo price in Manhattan increased 34.7% to $987,000 from the prior quarter’s median of $732,500.

The average sale price of co-ops increased 15.5% to a record $988,746 in the first quarter of 2005 from the last quarter. Also, the median price of co-ops exceeded $600,000 for the first time, rising 15.7% to $610,000.

Ms. Herman said that potential buyers frequently ask if now is a good time to get into the market. “If you have intentions of keeping it, you are not going to be hurt,” she said. “If you are looking to flip something in six months, if the market dips, you will.”

But, she said, there are no indications that a dip is likely in the near future.

Ms. Herman said she might start to worry if, for instance, the average time on the market started to go up, or the inventory started to rise. But even then, it is likely to be a gradual downturn. “It’s not like the stock market,” she said. “It usually doesn’t happen in one day. I look at the indicators, but so far they are good.”

In other findings in the Elliman report, the average price of luxury apartments rose 23.6% to $4.54 million from last quarter’s average of $3.69 million. The median price increased 22% to $3.6 million, up from $2.95 million last quarter, the Elliman report said.

While the Elliman report focuses on Manhattan as a whole, Halstead Property’s First Quarter Market Report, also released yesterday, follows trends in specific areas.

The Halstead report cites a 71% increase in the median price of apartments on the Lower East Side, partly due to an increase in the size of units being sold.

The average price of three-bedroom apartments on the East Side increased 40% over the last year, the largest gain of any size category in that market, reflecting high-end sales, the Halstead report said.

Overall, the Halstead report states, average sale prices of two-bedroom apartments on the West Side rose 23% over the last year.

The Halstead report also found an average price increase of 48% from last year among units with three or more bedrooms downtown.

The median price of apartments on Fifth and Park Avenues was $3 million, up from $1.79 million last year.

“There will probably be more modest gains going forward,” Mr. Miller said. “We just need to be concerned if there is a spike in rates from some external influence that isn’t foreseen, which is always a concern. But there is heightened sensitivity to that now because of the way the market has been improving.”

“Don’t expect the prices to fall anytime soon,” said the chief economist for Brown Harris Stevens, Gregory Heym. “People have been waiting and waiting for years for prices to come down.” He advises potential buyers to move quickly if they see something they like, but stresses that they should make sure it’s a home they are going to want to stay in for a few years.