A monster snowstorm has struck America’s north-east, causing travel chaos for Australians.

Airlines, including Qantas, cancelled around 6000 flights on Tuesday as cities braced for record snow and governors in New York, New Jersey, Pennsylvania and Virginia declared states of emergency.

Qantas’ US airline partner, American Airlines, cancelled all flights into the New York region’s three main airports: John F Kennedy; LaGuardia; and Newark.

Other Qantas codeshare flights from Boston and Philadelphia were also cancelled.

Qantas flight 12, a popular flight for Australian tourists flying home after American vacations, was scheduled to leave JFK at 8.55pm on Tuesday for Los Angeles but was cancelled.

The massive number of New York flight cancellations came despite the metropolitan area avoiding the storm’s biggest punch, with officials halving the city’s snowfall forecast to between 10 to 20cm.

New York state’s north and along the Pennsylvania border expected more than 70cm of snow.

“Mother Nature is an unpredictable lady sometimes,” New York Governor Andrew Cuomo told reporters.

Further north, in Boston, the city was expecting 30cm of snow and around 60cm in other parts of Massachusetts.

– AAP