Milwaukee – Cold bitter winds mark the start of the winter season as an Arctic blast of air chills 42 states this week, from the Canadian border down to the Gulf of Mexico, say forecasters.

It is being estimated that 200 million people are expected to be affected by the cold, with only Florida, Hawaii, and the Southwest being spared, according to forecasters.

Those states to feel the frigid temperatures this week will be states along the Canadian border and in the northern Rockies.

Winter storm warnings are in effect for Montana, North and South Dakota, Wyoming and Minnesota as they braced for a major snowstorm forecast for the leading edge of that Arctic blast, according to the National Weather Service.

The storm is set dump up to two feet (61 cm) of snow in parts of Minnesota, Michigan and Wisconsin by Tuesday, according to the service.

Monday also marks the start of two weeks of subfreezing temperatures in the Midwest, including Illinois and Missouri, forecasters said.

The cold is expected to dip into the Central Plains states by Tuesday, dropping the mercury by nearly 30 degrees (17 C) overnight in Oklahoma.

“The arctic blast will have the greatest shock over the central states,” said Chief Meteorologist Elliot Abrams.

For the Rockies and the plains, Tuesday and Wednesday will see low temperatures dipping below zero (-18 C), forecasters said.

The weather shift can be blamed on what forecasters call a polar vortex reaching into the United States from the north.

The polar vortex is a large pocket of very cold air, typically the coldest air in the Northern Hemisphere, which sits over the polar region.