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Heatwave looms for southeastern Australia

The southern states are set to sizzle for a prolonged period later this week, with maximums set to reach the mid to high 30s in the capital cities.  

A stubborn high pressure system over southern Australia will direct hot northerly winds over the southern states for several days before a trough arrives on the weekend.  

The run of hot days and warm nights should bring heatwave conditions to parts of SA, Vic, Tas and southwestern NSW from Thursday, November 21. Isolated areas of southern SA and western Vic are forecast to see severe heatwave conditions later this week.  

Image: Heatwave severity forecast for three days from Thursday, November 21 

The southern and southeastern capital cities daytime temperatures will reach 6 to 12°C above average mid to late this week: 

• Adelaide is forecast to see around 5 to 6 days above 29C starting Wednesday, November 20, with temperatures peaking at 35°C on Thursday and 37°C on Friday. 

• Melbourne’s mercury will soar into the mid 30s on Friday and/or Saturday depending on high cloud and rainfall.  

• Hobart’s maximum temperature should reach 28°C on Saturday. 

• Sydney is forecast to see temperatures in the mid to high 20s from the weekend into next week.  

• Brisbane is the exception this week with well below average temperatures forecast until early next week.  

 While Adelaide and Melbourne’s hottest days are not aligned, the cities should see some coincident heat with both capitals forecast to reach the mid to high 30s on Friday, November 22. This could increase the strain on the energy grid with increased demand in several states at the same time.  

Image: Maximum temperature forecast for Friday, November 22, according to ECMWF 

An unseasonably humid atmosphere over southern Australia, should make these temperatures feel up to 3°C warmer than the actual temperature increasing the demand on the energy grid. 

Unfortunately, there will be little relief overnight Thursday and Friday for those in Adelaide and Melbourne with minimums of 22 to 23°C forecast.  

Looking ahead, the southern capital cities temperatures should drop below the 30s later this week into next as the trough sweeps across the southeast.  

Meanwhile, the heat will push northeast towards NSW and Qld. There are very early signs that eastern Australia could see a run of heat mid to late next week, so keep an eye on the latest forecasts in the coming week.