Victoria, New South Wales, the ACT and southern Queensland have been hit by a sudden frigid chill, a chill not experienced this early in the year in decade or longer in many places.

Temperatures overnight plumeted five-to-10 degrees below average, five-to-10 degrees colder than the previous night in some areas, in calming winds and clearing skies in the wake of a cold front.

It got as cold as -9.4 degrees, at Perisher, -6.9 at Thredbo and -6.1 at Mt Hotham, helping maintain 10-to-20cm of fresh snow which had fallen in the previous 48 hours.

Getting this cold typically occurs in June or July, sometimes in August. In fact, Canberra (-5.4 degrees), Benalla (-3.3 degrees) and Cowra (-2.7 degrees) and Cobar (0.5 degrees) were colder last night than at anytime during last winter. Last night was also the coldest May night in 34 years in Cobar.

It was the coldest night this early in the year in 22 years in Ulladulla (6.5 degrees), Albury (-1.0), Katoomba (-1.1), 15 years in Dubbo (-2.5), Cowra and 10 years in Sydney (7.8 degrees in the city), Grenfell (-1.8), Narrandera (-1.4), Armidale (-4.1) and Canberra.

Image: Temperatures and synoptic pattern at about sunrise on Sunday 16 May

Clear skies allowed these places to warm quickly today in the sunshine despite the chilly winds.

Tonight looks like being another frosty one in northern and central NSW and southern Queensland due to lingering clear skies and dry calming winds in the chilly air.

Much of the ACT. Victoria, Tasmania and South Australia will benefit from a cloudy blanket and a burst of wind, due to a passing front, keeping frost away from most areas. This front will however, bring showers to the far southeast and a bit of snow to the Alps tonight.