Although we're still in the middle of autumn, a polar vortex is bringing an arctic blast and frigid temperatures this week to many parts of the United States.

As part of a polar vortex moves southward, many areas across of the country are expected to be hit with an abrupt chill. However, there will be some exceptions, including the Southwest, Hawaii, Alaska and South Florida, which will escape of the upcoming winter blast, reports Accuweather.com.

According to AccuWeather meteorologist Alex Sosnowski, the polar vortex is defined as "a large pocket of very cold air, typically the coldest air in the Northern Hemisphere, which sits over the polar region."

"Occasionally, this pocket of very cold air can get dislodged farther south than normal, leading to cold outbreaks in Canada and the U.S.," he explained.

The northern Rockies and Plains will be hit the hardest in the current outbreak, although many communities in these areas are already enduring the arrival of bitter cold weather. On Monday, temperatures lingered in the lower teens throughout most of the day in Montana and both North and South Dakota. Temperatures also dipped into the negative teen digitis in some spots, including Glasgow, Montana, on Monday night.

In addition to the arctic blast in the northern Rockies on Monday, forecasters predicted a snowstorm on its leading edge. Plus, the frigid air following the storm will lead to a freeze-up, and commuters will face icy travel conditions.

Later in the week, the cold will reach the I-95 corridor, while temperatures will also plummet throughout the Northwest and to the Gulf Coast.

The highs during the middle of the week will only peak in the teens and single digits, with subzero lows on Tuesday and Wednesday, the coldest days of the week across the northern Rockies and northern High Plains.

Back in January, the polar vortex prolonged a deep freeze in many Eastern States.

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