Just a week after declaring that 2013 was Australia's hottest year ever, local officials are warning this sunburned nation to brace for even worse weather, with a tsunami of heat expected to wash over almost all of Australia by Wednesday, leaving further devastation in its wake.

Bush fires, red alerts, emergency patient monitoring and even mass animal deaths have been recorded as the heat wave inches eastward, overcoming all national heat records and the towns that hold them.

According to Bureau of Meteorology forecaster Peter Zmijewski, extreme heat wave conditions are forging through the baking Nullabor Plains and spreading toward southeast Australia, with little or no relief in sight for inland areas already baked to a crisp after a year of record temperatures.

In its closely watched Annual Climate Statement, released last week, the bureau declared Australia's 2013 average temperatures were 1.2 degrees C above the historic average of 21.8 C, breaking all records.

All Australian states and regions recorded above-average temperatures in 2013, with Western Australia, South Australia and the Northern Territory all smashing annual temperature records.

The country recorded its hottest day on Jan 7 - a month that also saw the hottest week and hottest month since record-keeping began in 1910.

Zmijewski said that the eastern seaboard will need to prepare for the coming days.

In a special climate statement, the bureau said the latest heat wave, while "less extensive and prolonged" than that of 2013, was still singularly remarkable.

A nation surrounded by water, Australia is dry and extremely arid across massive distances in its "Red Heart".

The heat wave began on Dec 27 in eastern Western Australia and spread slowly north and east, setting records at 34 sites where data has been collected for 44 years.

This year, scorching heat has been festering in the Red Heart since December and is driving a veritable tsunami of heat across inland Australia toward the highly populated eastern coast.

The pain is being felt from Perth to Sydney, Queensland in the north all the way south to South Australia and even Tasmania.

Queensland already has baked through sizzling nights, with the statewide mean temperature on Jan 3 shattering the previous record by "an extraordinary 0.75 degrees", the Bureau of Meteorology said in a statement last week.

More than 10 percent of Queensland and almost 15 percent of New South Wales recorded their hottest days on record. Roma, in southern Queensland, broke its record high on three separate days within a one week period.

Reports of hundreds of thousands of bats simply dropping from the skies have been confirmed by sources at the Queensland Royal Society for the Prevention of Cruelty to Animals, with spokesman Michael Beatty telling reporters that mass deaths have been recorded at up to 25 separate colonies.

"The heat wave was basically a catastrophe for all the bat colonies in southeast Queensland," Beatty said.

South Australia and its isolated capital, Adelaide, is preparing for the worst. State Premier Jay Weatherill has urged people to consider their best bush-fire action plans, while nurses across the state are monitoring the vulnerable in the face of 43 C forecasts later in the week.

The State Emergency Service issued a rare extreme-heat warning, with weather conditions a risk to public safety.

Even the nation's capital, Canberra, is on red alert with the bureau forecasting highs of 39 C into the week.

On Tuesday, the anticipated sellout crowd for the all-important annual Prime Minister's XI cricket match is likely to go ahead in 37 C heat.

The slow-moving pall of heat is smashing temperature records everywhere and has been described by officials in the bureau as a "highly significant" event, even in the face of the announcement that 2013 was Australia's cruelest in more than a century of heat records.

Xinhua