Hot and windy conditions in Tasmania have sparked a bushfire at Dolphin Sands on the state's east coast.

That's now been downgraded from emergency level to watch and act but senior meteorologist Sarah Scully says conditions remain challenging. 

"Those winds have eased off with the wind warnings canceled however it is expected to remain quite gusty today and there are still a number of places than in through central and eastern parts of Tassie," she told ABC radio. 

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In regional NSW, a grass fire at Bulahdelah, north of Newcastle, has been upgraded to a Watch and Act Prepare Now level. 

This warning applies to Myall Creek Rd, Myall River Road and Nerong. 

The Pacific Highway is closed in both directions between Twelve Mile Creek and Nabiac.

Rural Fire Service crews remain on the ground and waterbombing aircraft are working to control the fire.

The RFS says the fire is burning on both sides of the highway.

In Victoria, a fire in Markwood, east of Wangaratta, has been reduced to a Watch and Act. 

Authorities say the bushfire spread has slowed for now, but the situation could change at any time. 

It is not safe to return to the area.

Earlier we heard from the bureau's senior meteorologist, Sarah Scully. 

She also told the ABC News Channel what this spells for the rest of the summer.

In short, "above-average temperatures" during the day and night.   

 "With regards to rainfall, large parts of Australia are expected to have below-average rainfall," she adds. 

"So that includes south-eastern parts like the Melbourne,  Adelaide and Tasmanian area.

"However, parts of eastern Australia including the east coast of Queensland have a chance of having above-average rainfall. 

"So a bit of a mixed bag with regards to our summer forecast, but one thing that's across the board is above-average temperatures. "

Hot weather is sweeping NSW, with temperatures forecast to reach low forties in some parts.

The weather is expected to continue tonight and Saturday.

Around 40 bush and grass fires are burning, with fire danger warnings in place and a number of total fire bans declared.

In Corowa, residents were caught off guard by "early" fire in a sign of "apathy", authorities told ABC Riverina. 

Emergency Services Minister Jihad Dib told Radio Sydney people needed to take extra care.

"Look out for vulnerable people, but if you can avoid being outdoors for physical exercise and work, especially in the heat of the day," he says.

"Be sensible about it. I think that's the most important thing."

Hello I'm Rachel Jewell and I am joining you as temperatures are expected to soar today.

The Bureau of Meteorology says the current heatwave is just the beginning of what could be one of Australia's hottest summers on record.

Earlier this morning senior meteorologist Sarah Scully spoke to ABC News Channel and says it's not just the daytime temperatures we need to keep an eye on.

"High temperatures are expected to continue in to tomorrow and it's not just the daytime temperatures though that are going to be high, it's also the overnight temperatures," she says.

"That's where that heatwave warning comes into play because the heatwave is when the body doesn't get a chance to recover from the high temperatures during the day in the overnight period."

Hello I'm Tessa Flemming and I'll be joining you as Australia swelters. 

A broad heatwave is expected to spread across the country.

Throughout southern states, the burst of heat is short and sharp, sending temperatures more than 10 degrees Celsius above average and raising fire dangers to extreme.

For the northern outback though, the heat will linger well into next week, with oppressive daily temperatures well above 40C.

We'd love to hear how you're feeling in your patch, if you want to send in a comment.