Ballarat is going for four consecutive days over 33 degrees later this week, with Friday expected to max out into what is predicted to be Ballarat's hottest ever December day.

After a relatively cool start to summer - so far, the average temperature has been just over two degrees below normal - the weather will heat up dramatically as a high pressure system which has been stationary over the west of the country finally starts to head east.

On Friday, Ballarat is predicted to hit 41 degrees, which if it comes through, will be officially the hottest December day every recorded in the city. Currently that sits at 40.6 degrees on December 31, 2005.

What is almost certain is that Ballarat will see three consecutive days above 37 degrees in a row, however the record will be dependent on what time the cool change arrives on Friday, with Saturday predicted to return to the 20s.

According to Weatherzone, the heatwave will be due to a large mass of hot air which will sweep across the country over the next 10 days. While it is difficult to predict where the hottest parts in the country will be, temperatures are predicted to hit at least 45 degrees somewhere in every mainland state and territory (except the ACT) this week.

A number of forecast models show that temperatures may even exceed 50 degrees in some points, most likely in northwest South Australia or southeast Western Australia.

Oak Valley in outback South Australia is forecast to hit 49 degrees on Wednesday. The hottest temperature ever recorded in Australia is 50.7 degrees at Oodnadatta Airport, also in South Australia, in 1960.

But some good news from the system is that winds are generally expected to be relatively light meaning conditions won't be conducive to fast-moving fires, however total fire ban days could be enforced.

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