With the mercury set to soar again at the weekend, it's becoming more likely regional vignerons will be called on to supply grapes to other vineyards.

But that's if our own vines can hold out for another six weeks, a tough task given temperatures in our region are predicted to hit 37 degrees today, 39 tomorrow and 38 on Sunday.

Yesterday's top of 37.4 even saw parents of pupils at Torrens Primary School being told they could pick their children up early from classes because of a lack of air conditioning.

Relief from yet another hot spell is not expected until next week, raising the fire threat for the ACT, and it's even worse for Victoria.

The state faces a never-seen-before bushfire risk tomorrow, with temperatures in the mid-40s and high winds expected to whip extreme fire conditions, worse than those that led to the deadly Ash Wednesday fires of 1983.

For NSW, temperatures are predicted to reach 44 degrees in Sydney's west on Sunday, and as high as 47 in the state's west.

The recent stretch of 40-plus days in the southern states has already caused irreparable damage to some of the country's most prestigious wine regions. Up to 80 per cent of crops on some vineyards have been destroyed and the industry has reported losses of more than $100million.

But Canberra winemakers are referring to the capital district as the rose among the thorns as their crops withstand the scorching temperatures as well as thunderstorms a few weeks ago.

Mount Majura Vineyard part owner Frank van de Loo said changing weather was what made the industry exciting.

''Each year has its own challenges and we will have to take it how it comes. But we will be watching it closely,'' he said.

The region is expecting a record crop of about 5000 tonnes , which would make it the only area to record an increase on last year. Many of the country's devastated vineyards are expected to look to Canberra to buy grapes to replenish their stocks.

Canberra winemaker Ken Helm said, ''The grapes for sale will be about 9 per cent of production and most will be taken up by wineries outside of the district this year ... I know the Hunter Valley and Griffith were looking.''

This would be positive for the region, but winemakers warn it will be at least a month before they pick the grapes.

Mr Helm said anything could happen in a day.

''The only concern is if there are hot days for an extended period and we don't want strong winds.''