Even if Con Ed has the heat in your apartment back on by the weekend, your Downtown office building may stay chilly until sometime next week — so hope for moderate temperatures or bring a sweater to work.

The forecast over the next five days is for daytime temps ranging from 47 to 53 degrees — with nighttime lows dipping to 37 degrees.

“We don’t know how long it will take to get steam to all those customers,” said Con Ed spokesman Mike Clendenin. “We expect it will take days if not longer for the steam service to come down the line.”

Clendenin said the two East Side steam plants were turned off as part of prep for Sandy, but that has left 550 buildings, most of them used primarily for office space and located below 14th Street (including the Trinity Real Estate properties and the sprawling residential Stuyvesant Town complex) without the steam that runs their heat and hot water.

The steam was turned off to save the system because when cold river water hits a hot cast iron steam pipe, the pipe cracks.

The buildings also need electricity first to run their own steam boilers, which then power, heat and cool the offices.