At least seven American states have declared a state of emergency in the wake of a huge winter storm that could result in the heaviest snowfall and coldest temperatures in more than 10 years.

According to the BBC, state authorities in Kansas, Missouri, Kentucky, Virginia, West Virginia, Arkansas and New Jersey have declared emergencies with schools shut down in some areas.

Thousands of flights have been delayed or cancelled, and several roads have been cut off due to the storm. 

Kansas is one of the most affected areas by the storm, which may cause the biggest snowfall and coldest weather in the U.S. in more than a decade.

“This could lead to the coldest January for the U.S. since 2011,” AccuWeather forecaster Dan DePodwin said before adding that the “temperatures that are well below historical average” could linger for a week.

Citing forecasters, the BBC reported that the huge winter storm is caused by the polar vortex – an area of cold air circling around the Arctic. 

The storm is expected to move eastward in the coming days, causing extreme weather conditions.