By Adrian Black in Wodonga

While southeast Australia breathes a sigh of relief after an intense but short-lived heatwave, the timing reminds Australians to prepare for a high-risk summer.

Temperatures pushed into the mid-40s in parts of NSW, Victoria, SA and Queensland on Monday in one of the hottest December days since 2019.

Despite a cold front easing conditions in southeast Australia overnight, total fire bans are still current in northwest Victoria and heatwave conditions are expected to persist for days in the NT and southern Queensland.

Brisbane, Mackay and even Townsville could meanwhile face heavy rain and flash flooding, with isolated downpours of up to 250mm forecast.

Insurers urge Australians to prepare for the season ahead, with NRMA research noting 42 per cent of wild weather claims it receives arrive in summer, retail claims executive general manager Luke Gallagher said.

“NRMA Insurance has received a claim due to extreme weather every four minutes and 39 seconds during summer for the past five years, which is a 60 per cent increase on the other seasons in the year,” he said.

The data showed more than one in 10 Australians had returned from holidays to find their homes damaged by thunderstorms, hail, floods, wild winds or bushfire.

“The lesson here is that ensuring your home is as well-protected as possible from extreme weather damage is never more important than at this time of year,” Mr Gallagher said.

While this week’s heatwave was relatively short-lived for the southeast part of the nation, these events are expected to become hotter, longer and more frequent, according to Monash University Associate Professor Ailie Gallant.

“These are some really hot temperatures for mid December that we haven’t had in quite a few years,” Dr Gallant told AAP, noting the increased fire risk.