Don't break out the flip flops and shorts just yet.

Another blast of arctic air is moving through the region this week.According to the National Weather Service, cold air has begun to push into the United States and through the Northeast, dropping the temperatures from the 50s this past weekend to below freezing today.A chance of snow is possible tonight through Wednesday morning and could bring up to three inches of snow in some areas. Temperatures are expected to be only in the 20s during the day, and single digits at night.These extreme cold systems seem to be becoming a trend this winter as the polar vortex, which has become a popular term in recent months, loosens its usually tight circulation over the northern hemisphere yet again.Thankfully, the Northeast will be spared subzero temperatures this week, but expect below average temperatures over the next few days.According to the Weather Channel, some areas in the Upper Midwest and Great Lakes will not be as lucky though. Daytime highs Tuesday through Thursday will be in the single digits to as low as 8-below zero in Minnesota.About the vortexBrian Edwards, meteorologist at AccuWeather, explained that the polar vortex is a pocket of arctic air typically centered over the North Pole.The vortex spins in a clockwise pattern, meaning that it pushes arctic air downward as the winds move over the pole. Its patterns determine how much cold air escapes the Arctic and travels south to areas like the United States, Europe and Asia.Typically, according to the National Weather Service, the polar vortex has strong and weak phases. When it is strong, the arctic air remains over the North Pole; but when it weakens, like it did in January and now this week, that is when extreme dips occur and the area gets blasted by extreme cold air.Edwards said that the weakened phases of the vortex occur when a large high pressure forms off the West Coast and Alaska. This displaces some of the arctic air and pushes it toward the United States.The current bitter blast that much of the Midwest and Northeast is experiencing may not be as cold as the January temperatures, but Edwards pointed out that February daytime temperatures average about 40 in Northeast Pennsylvania, about 20 degrees warmer than this week.He said the colder air in general will be warmer because of the higher sun angle and longer daytime hours."It won't be as bad as December and January," Edwards said. "But it will definitely be way below normal for February."The weekend doesn't look too much warmer, Edwards added, explaining that temperatures should remain below freezing, but rebound slightly.Next week also looks like the cold will remain.Setting recordsA number of cities across the country have broken temperature records a number of times this winter.NASA reported on Facebook on Feb. 18 that "On Jan. 6, 2014, alone, approximately 50 daily record low temperatures were set, from Colorado to Alabama to New York, according to the National Weather Service. In some places temperatures were 40 degrees Fahrenheit colder than average."According to Duluth News Tribune, Duluth, Minn., broke its record for most subzero days in a winter, which stood at 60 days, on Feb. 16.Minneapolis-St. Paul is also making a name for itself in the record books. The upcoming cold air will probably push the city into the top 10 most subzero temperatures ever recorded in a single winter, the local news station, KARE 11, reports.As of Monday morning, they have had 42 subzero temperatures this year, making it the 11th coldest winter on record since 1873.By the end of this week though, the city is expected to move to the ninth coldest.