Metro-North trains should be back on a regular weekday schedule by the Friday morning rush — after two and a half days of slow and irregular service as workers finished fire repairs, officials said.

The Harlem, Hudson, and New Haven lines should all be back to normal for their 300,000 daily riders, officials promised.

Meanwhile, city officials said the garden nursery where the fire originated did not have the proper permits to store gas used in its generator. A worker spilled fuel on Tuesday while filling up the hot machinery.

“This business owner did not apply for the necessary permits to store flammable materials in these quantities at this location,” a spokesperson for Mayor de Blasio said on Thursday afternoon. “Had the business followed the law, FDNY would have assessed the site and determined that this storage of flammable materials should not be allowed.”

The head of the MTA said it is the city’s job to keep the underside of the tresle safe.

It is city property,” said MTA chairman Thomas Prendergast.

The owners of the garden center that sparked the fire did not return calls for comment.