Those in Canberra have shivered through their coldest night since last winter with the mercury plunging well below zero. There are three key ingredients that bring cold nights: light winds, clear skies and a cool airmass. On Saturday morning a cold front delivered the cool airmass while a high pressure system behind the front provided the clear skies and light winds. These ingredients combined on Sunday morning to chill the nations capital to -5.3 degrees. This is five below the average and coldest morning in nearly a year. At 7am it was still hovering around -5, making a Sunday sleep-in that much more inviting. The cool airmass will linger over Canberra in the coming days while the high will continue to bring light winds and mostly clear night time skies. This means that the frosty mornings are likely to continue until at least midweek . Although it is unlikely to be as cold as it was this morning it is forecast to drop below zero each morning until Thursday. Increasing cloud should then trap some of the day time heat on Thursday night, allowing it remain above freezing on Friday morning.