Firefighters in New South Wales and Queensland are gearing up for a week of unseasonably warm weather as they continue to battle blazes across the two states.

And the former head of NSW’s urban fire service says early Australian bushfire seasons are here to stay, as he urges the federal government to step in as resources and firefighting assets stretch beyond current capacity.

Greg Mullins served as commissioner of Fire and Rescue NSW from 2004 until his retirement in 2017 and currently sits on the Climate Council, a national climate change communications body.

With NSW bushfires making an early mark in 2019 – including the destruction of nine homes over the past week in the state’s north – Mullins says authorities should prepare for more of the same in coming years.

He says the entire Australian strategy of tackling bushfires – sharing firefighting resources between states as the risk moves from northern states in spring to southern states in summer – is under threat.

Climate change has made nights and winters warmer, increasing the possibility extreme bushfires would burn in different states simultaneously.

“What’s becoming difficult is the whole paradigm of strategic firefighting in Australia – it was predicated on progressive fire seasons,” he says.

“As we saw last year and now, we’re getting simultaneous fire seasons.

“States are having to resource their own fires while other states are screaming out for help and there’ll be times when each state says, you’re on your own.”

Conditions have eased since the strong winds earlier this week fanned more than 130 fires across Queensland and New South Wales, but there are still 70 fires still burning in Queensland and 45 south of the border in NSW.

Jonathan How, a forecaster at the Bureau of Meteorology, told Guardian Australia it would be a very warm weekend across north-east New South Wales and south-east Queensland, and those conditions would extend into next week.

“The main reason we are seeing these very warm conditions is we have a very stubborn high pressure system sitting over the centre of the continent and so that is basically preventing any cooler conditions from making it any further north.”

He said there would be clear skies and temperatures between 6C and 10C above average for this time of year on the weekend, and up to 12C above average next week.

Most of the fire sites would experience temperatures in the high 20s and low 30s, he said.

“That’s going to lead to high to very high fire dangers, which will keep conditions quite challenging for fighting the fires.

“The one saviour for the firefighters is the winds aren’t as strong as what we saw last week.”

But winds could pick up later in the week when a cold front comes through on Thursday. He said there was no forecast for rain in the fire-affected areas in the next week.

John Bolger, acting commissioner for the Queensland Fire and Emergency Service, said a westerly wind change on Friday lowered the humidity and increased the temperature, meaning the 600 firefighters and 15 fire trucks in the field would be busy over the weekend.

“Peregian fires are pretty much contained. We did have a flare-up this afternoon but we were able to bomb that with helicopters,” he said.

“Our area of concern this weekend, among others around the state, is the Sarabah fires,” he said.

NSW Rural Fire Service inspector Ben Shepherd told Guardian Australia firefighters had been dealing with similar conditions for a few months.

“We’ve been dealing with above average temperatures and a very dry landscape for a number of months,” he said.

Quick Guide Climate change and bushfires Show Does climate change cause bushfires? The link between rising greenhouse gas emissions and increased bushfire risk is complex but, according to major science agencies, clear. Climate change does not create bushfires, but it can and does make them worse. A number of factors contribute to bushfire risk, including temperature, fuel load, dryness, wind speed and humidity. What is the evidence on rising temperatures? The Bureau of Meteorology and the CSIRO say Australia has warmed by 1C since 1910 and temperatures will increase in the future. The Intergovernmental Panel on Climate Change says it is extremely likely increased atmospheric concentrations of greenhouse gases since the mid-20th century is the main reason it is getting hotter. The Bushfire and Natural Hazards research centre says the variability of normal events sits on top of that. Warmer weather increases the number of days each year on which there is high or extreme bushfire risk. What other effects do carbon emissions have? Dry fuel load - the amount of forest and scrub available to burn - has been linked to rising emissions. Under the right conditions, carbon dioxide acts as a kind of fertiliser that increases plant growth. So is climate change making everything dryer? Dryness is more complicated. Complex computer models have not found a consistent climate change signal linked to rising CO2 in the decline in rain that has produced the current eastern Australian drought. But higher temperatures accelerate evaporation. They also extend the growing season for vegetation in many regions, leading to greater transpiration (the process by which water is drawn from the soil and evaporated from plant leaves and flowers). The result is that soils, vegetation and the air may be drier than they would have been with the same amount of rainfall in the past. What do recent weather patterns show? The year coming into the 2019-20 summer has been unusually warm and dry for large parts of Australia. Above average temperatures now occur most years and 2019 has been the fifth driest start to the year on record, and the driest since 1970. Is arson a factor in this year's extreme bushfires? Not a significant one. Two pieces of disinformation, that an “arson emergency”, rather than climate change, is behind the bushfires, and that “greenies” are preventing firefighters from reducing fuel loads in the Australian bush have spread across social media. They have found their way into major news outlets, the mouths of government MPs, and across the globe to Donald Trump Jr and prominent right-wing conspiracy theorists. NSW’s Rural Fire Service has said the major cause of ignition during the crisis has been dry lightning. Victoria police say they do not believe arson had a role in any of the destructive fires this summer. The RFS has also contradicted claims that environmentalists have been holding up hazard reduction work. Photograph: Regi Varghese/AAP

The difference for next week is the need to continue to fight the fires already ablaze. Of the 45 fires in the state, 12 have yet to be contained. A total of 400 firefighters will be kept in the field and at the height of the fires there were almost 1,000.

“It might not be as hot and windy as it was last Friday; we didn’t have the fires in the landscape at the time. So now we’re dealing with hundreds and thousands of hectares that are alight, and hundreds of kilometres of perimeters of fires that are alight,” he said.

“That, moving into next week, doesn’t bode well, and that’s why we are encouraging everyone to ensure their properties are prepared, regardless of whether you’re near these fires, or bushfire prone land.

“The landscape is so incredibly dry at the moment. We’re seeing fire behaviour that we would typically see in the middle of summer and that is obviously difficult for firefighters to control.”

Shepherd said people should make sure they had a plan in the event of a fire, and prepare by reducing fire risk by cleaning leaves from gutters, mowing lawns, trimming branches, and removing combustibles from the sides of houses.

The above-average spring temperatures are likely to continue over spring. Bom researchers reported last week in the Conversation that there could be months of above-average temperatures and below-average rainfall in large parts of NSW and Queensland as a result of record warm temperatures above Antarctica.

The Actuaries Institute’s quarterly climate index released this week also showed autumn 2019 ranked as the second-highest for extreme temperatures since the index started in 1981.

The Actuaries Institute chief executive, Elayne Grace, said there was a “growing urgency” to understand the occurrence of extremes in climate and the impacts of climate change on businesses and communities.

– Australian Associated Press contributed to this report