"FOR two long days in Australia's southeast it has been summer in name only.

Snow, hail, lightning, dust storms, raging winds, plummeting temperatures, rain and more rain – the full furies of winter have been unleashed on much of Victoria, South Australia and the eastern seaboard in the past 48 hours.

A 14-year-old boy from Melbourne's west is missing and feared drowned after being swept from a bridge. A Ballarat man is fighting for his life after a tree crashed into his moving car.

And a day after Sydney schoolgirl Klara Clausen was crushed by a tree while camping in atrocious weather conditions, a forestry worker was killed while clearing trees at a campsite near Shallow Crossing on the NSW south coast.

According to Bureau of Meteorology forecasters, the conditions were sparked when cold air surging northwards in a front collided with warm, humid air from the northeast, which had been flowing into an inland trough for most of the past week.

The results have been extraordinary. In Victoria, rain tumbled continuously for 31 hours. "That is very, very unusual," Mark Williams, BoM regional director, told The Australian.

In Melbourne, where thousands of homes were damaged and highways and train tracks cut off by the floods, incredulous inner-city workers watched huge trees float down the swollen Yarra River.

The water temperature at Sydney's beaches plunged from 22C to an Arctic 14C after westerly winds blew the surface water out to sea.

At Deniliquin, in southern NSW, the temperature reached just 11.7C – the lowest maximum in 140 years.

And after hailstones hammered Adelaide on Wednesday – for the first time in 30 years during February – locals were rewarded with the coldest February day in nine years yesterday. At 19.1C, it was 10C below average.

Senior BoM forecaster Elly Spark said the central pressure of the system, 982 hectopascals over Victoria, was remarkable.

The Victorian and NSW Alps were blanketed with snow. About 15-20cm fell at Mt Buller and Falls Creek, while at Thredbo, snow was still falling at 11am yesterday and icy winds of more than 130km/h were whipping through the village.

In Bass Strait, 20m waves battered the Spirit of Tasmania II, forcing it to abandon a treacherous crossing to Devonport.

And in Queensland, there were 10 lightning strikes every 60 seconds overnight on Wednesday. A fast-moving trough whipped up massive dust storms that reduced visibility to just 100m in parts of the state and sent temperatures plummeting." TM LI PHIL