It happened just before 8 a.m. on Grand Avenue in the University Heights section.
The fire burned through two multi-family homes, numbers 2321 and 2323.
In addition to the freezing cold, FDNY officials say there was a car parked in front of the hydrant.
Firefighters had to cut holes in the roof to get water into the building and it took some 140 firefighters to bring the blaze under control.
Menya Wienn and her nine kids, including several young children and a baby, were home when smoke filled their living room.
"It started it the wall and so it was real smoky," Wienn said. "So, I didn't really see much, but I was able to get my kids out, it was pretty scary."
The cold also caused delays in getting water onto the fire as firefighters say they had difficulties stretching the line.
"It's 23 degrees out and we had some good wind conditions today. It made it very difficult for the companies to stretch the line," said FDNY Deputy Chief Michele Fitzsimmons. "We were making sure no one slipped on the ice as they were trying to move around in the different operations."
No one was injured and the cause of the fire is under investigation.
The Red Cross said it is assisting the displaced families. They say what the victims really need besides a home is warm clothing.
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