Monday may have been Australia's driest day since weather records began 137 years ago.

A November 11 forecast map showed zero rainfall predicted for the entire mainland, with small amounts expected in Tasmania.

Bureau of Meteorology staff confirmed on Tuesday that just about every region of Australia had been dry.

A spokesman said: 'While it remained dry across most of Australia, during the 24 hours to 9am today rainfall was recorded in locations in both Victoria and Tasmania.

There was very little rain forecast in Australia yesterday in what may have been one of the driest days in the nation's history

'In Victoria, totals were mostly below 3 mm (5 mm at Ferny Creek). Some over 10 mm in Tasmania.'

If there had been no rain at all, that would have been a first for the nation.

'The team can't comprehensively identify a day in our records where there hasn't been rain somewhere on continental Australia,' a bureau spokesman said.

It comes as Sydney residents living near bushland were warned to be prepared to evacuate on Tuesday as the city faces an 'unprecedented level of bushfire danger'.

The city is facing 'catastrophic' conditions with fears 37C temperatures - along with 60km/h winds and low levels of humidity - could produce the 'perfect firestorm'.

About 100,000 homes in the Sydney area are said to be at risk, with 31,500 of those in the city's north.

The Army is ready to deploy helicopters to evacuate residents whose lives are endangered amid warnings of 'the most dangerous bushfire week this nation has ever seen'.

Blaze: A firefighter battles the flames during bushfires near Taree on the mid-north coast of New South Wales on Monday

'Some fires may start and spread so quickly there is little time for a warning, so do not wait and see,' the Rural Fire Service said on Monday.

'There are simply not enough fire trucks for every house. If you call for help, you may not get it. Do not expect a firetruck. Do not expect a knock on the door. Do not expect a phone call. Your safest option will always be to leave early.'

On Tuesday morning, RFS Commissioner Shane Fitzsimmons said 50 fires were burning across NSW and around 25 were uncontained.

None have reached the emergency level - but he expects some to do so today due to the 'catastrophic' conditions. Winds around Sydney are forecast to pick up mid morning and reach up to 90kmh after 6pm, meaning fires would spread rapidly.