Air conditioners will be humming and fire crews will be on alert as South-eastern Australia prepared for a scorching start to the week.

The Bureau of Meteorology is expecting Sydney’s centre to swelter through 36C on Tuesday before hitting 37C on Wednesday.

The city’s west, including Penrith, will suffer the worst of the heatwave with temperatures of 39C and 38C on Tuesday and Wednesday respectively amid warnings Sydney’s beaches will bring little relief from the heat.

The Bureau of Meteorology (BoM) has a severe fire danger warning in place for the greater Sydney region, along with the Lower Central West Plains, Eastern Riverina, Southern Riverina and the Northern Riverina areas.

The BoM expects the fire danger to likely continue through to Wednesday, a spokeswoman said.

Victoria is forecast to swelter under similar temperatures with mid-to-high 30s expected for Tuesday.

“In Melbourne we are forecasting a top of 34C, but across the north of the state we are looking at temperatures in the high 30s – 39C at Swan Hill, and 38C at Mildura and Echuca,” a BoM spokesman told The New Daily.

Hot and dry conditions across Victoria on Tuesday with fresh and gusty north to north-westerly winds means the northern parts of the state will be on high alert for fires.

“We do have total fire bans across the north of the state for tomorrow, as well with severe fire danger,” the BoM spokesman said.

“We do have northerly winds picking up on Tuesday and that will help get those temperatures get up a bit more – that also drives that fire danger as well.

“The combination of high temperatures and strengthening winds will lead to that high risk.”

Mallee, Wimmera, Northern Country and the North East districts are most at risk.

Fire Weather Warning issued for Tuesday: https://t.co/HLs2UYFQyQ. Check @CFA_Updates for latest info and #TotalFireBan areas. pic.twitter.com/XuS4ZIq6Li

— Bureau of Meteorology, Victoria (@BOM_Vic) December 12, 2016

The rest of the week will bring days in the low 20Cs for the Victorian capital, dropping to below average for this time of year with a cool change and potential rain patches late afternoon on Tuesday.

Adelaide is also expecting a searing start to the week, with the mercury hitting 36 on Tuesday.

Wednesday onwards will bring some relief with the temperature dropping to the mid-20s.

Brisbane will ease into the week with temperatures hitting 29 on Tuesday and 31 on Wednesday, before heating up on Thursday to 32.

The long-term forecast is looking good for Christmas in Melbourne and Sydney, with a predicted 31 and 27 respectively, while Perth will swelter through 36 degrees.

Meanwhile, parts of northern Tasmania are on alert with damaging winds forecast to could contribute to a high fire-danger threat.

The BoM reports that a front is due to hit the island state on Tuesday morning bringing wind gusts in excess of 100 km/h, affecting the centres of Devonport, Currie, Scottsdale, Whitemark, Bridport and St Helens.

As the front passes across Tasmania combining winds, temperatures in the high 20Cs and low humidity, the east and southeast parts will be subject to a very high fire danger warning, the BoM said.

– with Rose Donohoe/AAP