New York City and state officials overnight declared a state of emergency, closing schools and public transport and ordering the mandatory evacuation of Lower Manhattan, which houses the city’s financial district.

NYSE Euronext, operator of the New York Stock Exchange, said today it would close its markets on Monday and possibly Tuesday.

The NYSE earlier said it would close the physical floor, but continue electronic trading when the market opens tonight Australian time.

“We support the consensus of the markets and the regulatory community that the dangerous conditions developing as a result of Hurricane Sandy will make it extremely difficult to ensure the safety of our people and communities, and safety must be our first priority,” it said.

“We will work with the industry to determine the next steps in restoring trading as soon as the situation permits.”

It is the first time the US markets have closed for weather-related reasons since Hurricane Gloria in September 1985.

The New York Mercantile Exchange will also be closed, although trading will continue electronically.

Bloomberg reported that sandbags had been stacked around the NYSE and broader financial district in anticipation of the storm.

In its latest update, the US National Weather Service said Sandy was about to begin its northward turn, bringing a “life-threatening” storm surge, coastal hurricane winds and heavy Appalachian snow.

The storm is expected to move over the coast of the mid-Atlantic US states on Monday night local time (Tuesday morning Australian time).