Each state and territory is to be affected by elevated fire danger in coming days, with southern states copping the worst of it as very hot gusty winds are followed by a cooler, gusty change.

Brett Dutschke from Weather Zone said the good news was that the fire danger will not reach the heights of recent weeks, with winds not quite as dry, hot or strong, however conditions would still pose great concern to fire fighters and those living close to the bush and high grass.

"The very hot and gusty northwesterly winds will increase the fire danger, but for some areas, the cooler southerly change will be more of a problem for fire fighters," Mr Dutschtke said.

"The cooler southerlies will be drier and stronger than the northerlies."

He said northwesterly winds were drawing heat to southern states from the Western Australian Interior, where temperatures have been reaching the mid 40s in the last few days.

The WA Interior is heating up to the mid-to-high 40s today, tomorrow and Friday and the state's Goldfields is reaching the low-to-mid 40s today, causing fire danger to increase.

Heat is also increasing in South Australia, but will peak in the south of the state on Thursday, the same day it peaks across most of Tasmania and Victoria.

For the ACT, New South Wales, southern Northern Territory and southwestern Queensland, Friday is looking like the hottest day for most areas.

Over the weekend the heat will move from northern NSW to the rest of southern and western Queensland and inland areas of the NT and WA.

"While fire danger will be severe or extreme in some areas on the hottest day, it will still remain quite high for at least 24 hours after the cooler southerly change arrives," Mr Dutschke said.

"Looking ahead to next week, the heat will return, but it is not looking as hot as this week. Humidity will also be higher with help from moisture streaming down from the strengthening monsoon in the tropics. As a result, fire danger should not get as high."