Wet weather over the next three days could spoil the Australia Day long weekend for some parts of the country, although mostly sunny skies are expected in Perth, Adelaide and Melbourne.

A mix of rain and sunshine is forecast throughout the country with damaging winds and rain expected in north Queensland as Tropical Cyclone Kirrily is forecast to cross the coast overnight.

After Birdsville in western Queensland hit a record high of 49.4 degrees Celsius on Thursday, extreme weather warnings are in place for a number of states, with extreme heatwaves forecast inland.

Here's a look at what the Bureau of Meteorology forecasts the weather to look like over the next three days in each state and territory:

ACT

The long weekend in Canberra may get off to a wet start, with a shower or two forecast on Australia Day, most likely in the morning and afternoon.

But Saturday and Sunday are forecast to be mostly sunny. 

A top of 27 is expected on Friday, as temperatures are forecast to increase over the weekend, with maximums of 28 predicted on Saturday and 29 on Sunday.

New South Wales

Sydney is expected to see some wet weather over the next three days, with a medium chance of showers forecast for Friday, Saturday and Sunday.

The rain is expected to bring some relief in the later afternoon and evening today, with a maximum of 35 forecast for Friday.

Things are expected to cool off the rest of the long weekend with highs of 26 expected on Saturday and Sunday. 

Inland temperatures are expected to drop off slightly over the next three days, after Smithville observation centre in north-west NSW hit a high of 47.5 degrees on Thursday. 

An extreme heatwave warning is in place for the next three days for the Mid-North Coast district, with severe heatwave warnings also in place for Northern Rivers, Hunter, Northern Tablelands, Metropolitan, Illawarra, Central Tablelands, North West Slopes and Plains, Central West Slopes and Plains and Upper Western forecast districts.

An extreme fire weather warning is also in place for the Greater Hunter region.

Northern Territory

A wet long weekend is expected in and around Darwin, with heavy showers and possible storms forecast throughout Friday, Saturday and Sunday.

While temperatures are not expected to rise above 31 on Saturday and Sunday, nights are expected to stay very warm, with minimums of 25 forecast for Friday and Saturday and a low of 26 predicted for Sunday.   

In Alice Springs a possible shower is expected today, with weather remaining hot throughout the long weekend. 

Highs of 38 are expected on Friday and Sunday, with a top of 36 forecast for Saturday. 

A severe heatwave warning is in place until Saturday for the Simpson District. 

While a flood watch is in place for Sunday for Barkly, Central Desert Region, Georgina and Eyre Creek areas, with the tropical low expected to approach the NT from Queensland on Sunday. 

Queensland

Warm temperatures and possible thunderstorms are predicted for Brisbane this weekend, with an expected high of 36 forecast for Saturday, cooling off to a high of 32 on Sunday.

There's a slight chance of a shower forecast for Australia Day, most likely in the late morning or afternoon, with temperatures expected to top off at 32 degrees.

Inland, temperatures in Birdsville are expected to drop off to 46 degrees on Friday, and 40 degrees on Saturday and Sunday, after the western Queensland town hit a high of 49.4 yesterday.