By Lauren Casey

PHILADELPHIA (CBS) — An Arctic air mass is responsible for the deep freeze over the Delaware and Lehigh Valleys on Tuesday.  The arctic air will reinforce the cold to yield the coldest day in three years.

The air mass was hanging out over icy Greenland about a week ago. Now, the arctic air mass has shifted over the Northeast Region.  Wind chills Tuesday morning were near zero degrees in Philadelphia from the bone-chilling breeze.  In areas north and west of the city, temperatures nosedived reaching sub-zero digits earlier Tuesday morning.

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The Poconos can expect dangerous wind chills, dropping temperatures to -20 degrees. In these conditions, frostbite or hypothermia can set in with prolonged exposure.

Tuesday’s forecast high of 21 degrees would make for the fifth-coldest Jan. 11 ever and the coldest day in Philadelphia since Feb. 1, 2019. Daytime highs across the region will be 15-20 degrees below seasonal averages.

The city could reach a record low forecast on Wednesday morning at 13 degrees. By then, winds will subside. The record is 14 degrees, which was set in 1981.

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Temperatures slowly crawl out of teens and 20s by Wednesday afternoon.  

Other than the frigid temperatures, the forecast stays relatively quiet. Highs will be closer to average on Wednesday, and slightly above average by Thursday afternoon.  

The rest of the week remains quiet and snow or rain-free. 

A fast-moving clipper may bring the Philly region a round of snow showers late in the day on Saturday. That forecast is still evolving.

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CBS3 Meteorologist Llarisa Abreu contributed to this report.