Forecasters said the latest storm appeared weaker than first thought, but it still carried the threat of high winds and storm surges that could cause further damage to the already weakened infrastructure of the country's most densely populated region.
Hundreds of thousands remained without power as temperatures hit freezing at night, and finding them emergency housing - in some cases, for the long term - was the greatest challenge.
"Even though it's not anywhere near as strong as Sandy - nor strong enough, in normal times, for us to evacuate anybody - out of precaution and because of the changing physical circumstances, we are going to go to some small areas and ask those people to go to higher ground," Mr Bloomberg said.
Winds were kicking up in New Jersey, and some battered shore communities were ordering mandatory evacuations for later in the day. But many were deciding to stay, worried about their empty homes being looted.
The Federal Emergency Management Agency put a number to the storm's homeless in New York and New Jersey, saying 95,000 people were eligible for emergency housing assistance. Just under a million people were still without power in the region.
Storm surges along the coasts of New Jersey and New York were expected to reach 3 feet (0.9 metres), only half to a third of what the hurricane-driven Sandy caused last week. But Sandy destroyed some protective dunes, especially in New Jersey, making even a weaker surge dangerous.
High winds which could reach 65 mph could stall power restoration efforts or cause further outages.
New York City was closing all parks, playgrounds and beaches and ordering all construction sites to be secured. On Tuesday evening, Mr Bloomberg ordered three nursing homes and an adult care facility evacuated from Queens' vulnerable Rockaway Peninsula.