The frigid arctic air that arrived after a January storm brought over a foot (30 cm) of snow and sleet to the Northeast, causing the snow to begin melting on Sunday. Tragically, a 12-year-old girl in a Chicago suburb died when a snow fort she had built collapsed on her after church on Sunday, according to the Arlington Heights Police Department. A 9-year-old girl who was playing with her was treated for hypothermia after being rescued from the snow and is expected to survive. Temperatures dropped to single-digits Fahrenheit (about -20 C) from New York City to Boston and throughout northern New England, causing the melting snow to freeze late Sunday and early Monday, as reported by Marc Chenard at the National Weather Service’s Weather Prediction Center in College Park, Maryland. Winds reaching up to 30 to 40 miles per hour (48-64 kph) brought dangerously cold wind chill temperatures. Chenard stated that the current weather conditions are extremely dangerous, with temperatures dropping to negative 20s in Minnesota and Wisconsin. Boston will be at 3 degrees Fahrenheit this morning, with wind chills of minus 12 or lower. New York City and Washington D.C. will also experience similar temperatures, possibly reaching the teens later in the day, setting record or near-record lows. The National Weather Service has issued wind-chill advisories and warnings for more than 10 states, from North Dakota to East Coast cities. Predicted high temperatures for Monday are 17 Fahrenheit for New York City and 12 F for Boston. A large number of Americans were not working on Monday due to either the holiday or being furloughed federal government employees impacted by the ongoing shutdown, which is the longest in US history. The shutdown is a result of disagreement over funding for President Donald Trump's border wall plans. Flight delays totaled over 7,500 flights, primarily in New York and New England, as reported by FlightAware.com, a decrease from the previous day's total of over 14,000 delays. Tuesday's weather is expected to be slightly warmer, with temperatures in the low 20s Fahrenheit in the Northeast, according to Chenard.