This summer, the city has experienced a record number of days with temperatures exceeding 90 degrees. Perhaps the sizzling heat is affecting sales of residential rental apartment buildings and construction of condominium developments, which have reached a staggering pace and record levels.

Last week, real estate investor Richard Kalikow and Manchester Real Estate, in partnership with O’Connor Capital Partners, agreed to pay $636 million for a 19-story, 587-unit rental apartment building, the Manhattan House, occupying an entire block on East 66th and East 67th streets between Second and Third avenues. The seller is New York Life, which developed the property in 1950.

The Macklowe Organization has been very busy this summer. Two weeks ago, it agreed to sell its 41-story, 409-unit residential rental building, the River Terrace, at 515 E. 72nd St., to a partnership including C&K Properties, David Werner, and other investors, for about $363 million. Construction is under way at the Macklowe Organization’s 31-story, 88-unit condominium development called Three Ten East Fifty Third Street, at the corner of Second Avenue.

New York’s premier residential developer, Glenwood Management, led by Leonard Litwin, sold the Sutton Hotel to Alchemy Partners in June for about $53 million. Alchemy plans to convert the property into a residential condominium. This summer, Glenwood sold two office buildings, at 123 William St. and 55 John St., for $120 million. There were reports last week that Glenwood is planning to sell the 30-year-old, 35-story Marlborough House, which has 269 units and is at 235 E. 40th St., on the corner of Second Avenue. The property should fetch close to $200 million.

A prize collection of four residential rental apartment buildings, known as The Platinum Portfolio, at 20 Park Ave., 41 Park Ave., 10 Downing St., and 167 E. 82nd St., is expected to be sold later this summer. Industry insiders expect the buildings to fetch close to $175 million.

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Jack Resnick & Sons has built thousands of residences in Manhattan over the past four decades. Construction is under way at the company’s newest development at 200 Chambers St. in TriBeCa, a 258-unit residential condominium. According to industry insiders, the winning bidder will be selected later this month for the sale of its 41-story, 300-unit rental tower, the Gershwin, at 250 W. 50th St., on the corner of Eighth Avenue. The property is expected to sell for about $350 million. A variety of seasoned real estate investors have bid on the property.

One of the most active developers of residential condominiums in Manhattan is Clarett Capital, LLC. Earlier this year, the first residents moved into the OPUS, a 22-story, 64-unit condominium building at 2770 W.107th St. and Broadway. Last week, Clarett Capital, a joint venture between the Clarett Group and Prudential Real Estate Investors, sold the 7,500-square-foot retail condominium in the building for $18.6 million, or $2,480 a square foot. The tenants of the retail site are Lenscrafters and a Bank of America branch. Clarett is developing six residential condominiums in New York City.

Construction is under way on a 36-story, 57-unit condominium development, Plaza 57, at 212 E. 57th St., off Third Avenue, on the site of the former Sutton Theater. In addition, the company is developing a 54-story, 138-unit residential condominium, the Sky House, at 11 E. 29th St., and a 13-story residential condo building, the Chelsea House, which has 64 units, at 131 W. 19th St.

Across the street from Clarett’s Plaza 57 development, on the former two-story site of the electronics store The Wiz, at 212 E. 57th St., Broadway Management is in the final stages of its new residential condominium tower, Sutton 57, which has 37 luxury units. East of this project, at 228 E. 57th St., is P.S. 59, the Beekman Hill International School. The Board of Education is preparing to sell the property to make way for another condominium. One block east of this site is 330 E. 57th St., where a 16-story, 15-unit luxury condominium building is nearing completion. It is being developed by Cohen Brothers Realty Company.

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Edison Properties LLC, one of the tristate region’s largest owners and operators of parking lots and garages, as well as owners of Manhattan Mini-Storage, is planning to develop residential properties on its sites in Manhattan. A few weeks ago, Edison applied for a special permit from the city’s Planning Commission to develop its parking lot site at 501 W. 17th St. The site occupies a full city block bounded by West 17th and West 18th streets and 10th and 11th avenues. On the site, they plan to build 869 residential condominium units. The site is now occupied by a 377-space parking lot leased by the Drug Enforcement Administration. The lease runs through 2007. Edison also operates a parking lot at 207-215 East Houston Street, directly across from the famed Katz’s Delicatessen. According to industry insiders, it is planning to build a residential rental building, which may also house a Manhattan Mini-Storage on the lower floors.

A few years ago, Edison sold its parking lot site at 210 Lafayette St., to a partnership that included Andre Balazs. Mr. Balazs, Richard Gluckman, and Cape Advisors are completing an 11-story luxury condominium known as One Kenmare Square at the intersection of Cleveland Place and Kenmare and Lafayette streets. Mr. Balazs is also developing a new project, 40 Mercer, a 41-unit luxury loft building on Grand Street between Mercer and Broadway in SoHo. In June 2004, Mr. Balazs paid $24 million for a site boarded by West Street, West 13th Street, Washington Street, and Little West 12th Street, where he plans to build the city’s first Standard Hotel. Construction is scheduled to begin this fall.

Many question whether New York City can absorb the volume of new and converted condominiums. Prominent developers say the demand is there and people are willing to pay record prices per square foot. Demand may be strong, but few realize that residential mortgage rates have risen four times in the past month. The big question in the market is, when these new buildings are completed (within 12 to 18 months) and the offering plans for the conversions are released, will people have the appetite to buy at higher mortgage rates and perhaps a different business environment?

Mr. Stoler is a television broadcaster and vice president at First American Title Insurance Company of New York. He can be reached at mstoler@firstam.com.