A mid-summer heatwave sweeping across southeastern Australia during the next few days could cause Melbourne to sweat through its hottest weekend in a decade.

Northwesterly winds developing ahead of a low pressure trough will cause a stream of hot air to drift across southeastern Australia between now and Monday next week. This hot air will cause temperatures to stay high enough for long enough to be classified as a Severe heatwave in parts of Victoria, NSW, Tasmania and SA.

Image: Heatwave severity forecast for the three days starting on Friday, January 3.

Some areas in SA will see temperatures reach the low-to-mid forties between Friday and Monday. Adelaide is forecast to reach about 36°C on Friday and Saturday and could see minimums up in the mid-twenties on both mornings this weekend.

In Vic, the hottest air will arrive on the weekend and should cause daytime temperatures to breach 40°C in the state’s north. Some areas in southern Vic could get close to 40°C as well, including the Melbourne region.

Melbourne is forecast to reach 37 to 38°C on Saturday and Sunday, but there is a good chance the temperate will near 39°C on both days. If Saturday and Sunday both rise above 37.8°C, this will be the city’s hottest weekend since 2014.

Image: Daily forecast on the Weatherzone app showing the upcoming heat in Melbourne. Valid at 11am AEDT on January 3, 2025.

Parts of Tas will reach the low-thirties this weekend as temperatures climb more than 5°C above average for the middle of summer. Hobart’s warmest day will be on Saturday when the mercury is expected to reach about 28°C, six above average for this time of year.

NSW and the ACT will get their warmest weather between Saturday and Monday. Canberra is predicted to reach the mid-thirties on each of these three days. In Sydney, the city can also expect a couple of days in the mid-thirties on Sunday and Monday, although temperatures will be closer to 40°C in the western suburbs on both days.

Image: Forecast maximum temperature on Sunday.

This heat will help elevate fire danger ratings in parts of southeastern Australia over the next few days. Severe fire danger has been predicted in some areas of SA and western Vic on Saturday and Sunday, with high fire danger also anticipated in parts of Tas and NSW in the coming days.

While this heatwave won’t break records, it may still pose health risks and affect transport networks and other infrastructure. Visit the Australian Red Cross website for more information on how to stay safe during a heatwave.