The most powerful front in a few years will arrive this weekend, bringing strong cold winds, showers, hail and snow then lead to frost across about two thirds of Australia. From this weekend to next Wednesday much of South Australia, Tasmania, Victoria, New South Wales, the ACT, Queensland and the Northern Territory will experience its coldest spell in at least two years, more than five years in some places. Temperatures will drop three-to-seven degrees below average for four or five days running. Hawker, in the Flinders Ranges, should average a maximum temperature of about 12 degrees, making it the coldest four day spell in four years. Canberra can expect an average maximum of about eight degrees over four days. The last time the nation's capital averaged a maximum of less than nine degrees over four days was in June 2009. Sydney is forecast an average maximum of 15 degrees over four days, which would make it the city's coldest spell in two years. Further north, Charleville and Alice Springs, well north of where showers are likely to reach, can prepare themselves for their coldest four-day spell in three years. Charleville should reach an average maximum of 15 degrees each day and Alice should average only eight degrees, combining night-time and daytime temperatures. As far as showers go, they will be widespread but only just reach northern SA and southern Queensland and should be heaviest in eastern Victoria and southeastern NSW, where more than 50mm is possible. These showers will at times and in some places contain small hail and combining with the bitterly cold and strong winds will add to an already exceptional chill, making the actual temperature feel as much as five degrees colder. And the snow should fall almost right along the Victorian and NSW ranges, falling as low as 600 metres, most likely in southern-most parts. This will be great news for the snow resorts which are in for a 20-to-50 centimetre powdery layer. By early next week, a high pressure system should cause brisk wind to ease, showers, snow and cloud to clear, providing the perfect ingredients for frost to form. And frost is highly likely to become severe in the typically frost-prone areas.