US weather: 'So cold boiling water freezes in mid-air'
Parts of the US are braced for potentially record-breaking low temperatures as a "polar vortex" brings more freezing weather.
A winter storm has already blanketed areas of Canada and the north-eastern US with up to 2ft (60 cm) of snow.
This is how ABC News' reporter Gio Benitez is covering the story in Chicago.
- From the section US & Canada