Australia Weather News

In much of Australia, finding ways to withstand and adapt to extreme summer heat is simply a way of life.

Regular summer tops of 40 degrees Celsius in Adelaide and Perth, high humidity 30s in Darwin and the tropics, and dry lingering heat in Sydney and Melbourne are a part of life on the dry continent.

And then there's the standard eye rolling when reports of a "heatwave" arrive from the United Kingdom when it approaches the mid-20s, and crowds flock to beaches.

But it's not that different in Tasmania.

This weekend, parts of the island state are experiencing a "severe heatwave" with temperatures in the high 20s and overnight lows in the high teens.

So why is a severe heatwave in Tasmania akin to a relatively mild summer's day on the mainland?

It comes down to the concept of an "excess heat factor" and the resilience of people, towns and buildings.

Lower temperatures, higher UV

The Bureau of Meteorology (BOM) uses this concept when it declares heatwaves — adjusting to each region's climatological temperatures.

"We have heatwaves under relatively mild temperatures in Tasmania, because people feel the heat differently in different parts of the country," senior meteorologist Simon Louis said.

"In Darwin, they're going to feel the heat differently to Adelaide, and then again, differently to Hobart."

A week of persistent north-easterlies has brought much more humid conditions than usual to Tasmania, resulting in higher overnight temperatures.

It's something that Tasmanians might only experience once a year, and rarely for protracted periods.

"It's really that combination of warm days, but then much warmer than usual overnight periods that's leading to the heatwave," Mr Louis said.

And then during the days, Tasmanians have to contend with higher UV ratings than much of mainland Australia.

It's consistently at damaging levels from September to April, and will be at extreme levels throughout the weekend.

"In Tasmania, we actually have higher melanoma rates than most of the country, besides Queensland," Cancer Council Tasmania acting chief executive officer Abby Smith said.

"It's so important when people go outside to protect themselves."

As is often the case with higher temperatures and humidity, the hot weather will likely end on Saturday night when a band of thunderstorms crosses the state.

Urban design a factor

There are a range of other factors that make higher temperatures more dangerous in Tasmania.

The state has a higher proportion of elderly residents, more people with underlying health conditions, older housing stock, poorer access to healthcare and towns and suburbs that are increasingly devoid of tree coverage.

A study last year by the Menzies Institute for Medical Research estimated that there were 86 heatwave-related deaths in Tasmania from 2010 to 2018.

It also found that low intensity heatwaves had higher mortality rates than severe heatwaves.

Another study by the University of Tasmania used Launceston as a case study in urban resilience to heatwaves.

The parts of the city that experience hotter conditions had less tree canopy cover, and more residents susceptible to heat vulnerability.

It found a range of flaws in urban design.

"The Tasmanian planning system and planning policies presently are seen to have limited value in protecting vegetation and mitigating extreme heat," the report stated.

"Trees are lost to clearing when sites and levelled and during construction of buildings, when newly planted street trees can be damaged by tradespeople."

It's a similar scene across suburban Australia, where rows of houses in new developments have limited tree coverage.

The CSIRO's climate analogues tool projects that Launceston's 2090 climate could be more similar to Wagga Wagga, while Hobart could be akin to Bendigo.

It raises the prospect of 40C summer temperatures — and a need to change approaches to heat resilience in Tasmania.

"Steps need to be taken now to prepare the state's settlements for a hotter future. Indeed, Launceston is expected to see a fourfold increase in heatwaves," the report concludes.

Too many homes 'unbearably hot, dangerously cold'

As housing prices continue to rise, an increasing number of Australians are left to indefinitely rely on the rental market.

But there are no minimum standards for air conditioning or cooling.

Only the ACT and Victoria have moved towards requiring energy efficiency standards in rental properties.

National Association of Renters’ Organisations chief executive officer Leo Patterson Ross said all Australians deserve to live in a home that is resilient to hot and cold weather.

"Cooling and air-conditioning are often required, especially in apartments, to ensure premises are able to be kept within World Health Organization standards," he said.

"Far too many homes across the country are unbearably hot in summer, dangerously cold in winter, or both.

"It is clear that legislating these requirements is the most effective way to ensure they happen, and incentives and subsidies can assist in ensuring roll-out happens with little dispute."

In Tasmania, there are no requirements for insulation or for fly screens on windows.

Tasmanian Tenants Union solicitor Alex Bomford said the state's older housing stock was often difficult to keep cool in summer.

"Minimum standards in Tasmania are weak and don't provide any assistance whatsoever to mitigate or minimise heat," he said.

"Given the growing impact of climate change, it's something that the government will need to address."