Once was bad enough, but smoke from Australia’s devastating bushfires is set to return to the country to complete a round-the-world trip that has seen it impact on air quality as far away as South America.

By January 8, the smoke had made its way halfway around the world and will make at least one full circuit, according to scientists at NASA, citing satellite tracking data. New Zealand experienced severe air quality issues, while hazy skies and colourful sunsets and sunrises were seen in parts of Chile and Argentina.

“The fires in Australia are not just causing devastation locally,” NASA said in a media release. “The unprecedented conditions that include searing heat combined with historic dryness, have led to the formation of an unusually large number of pyrocumulonimbus events.”

The uplift of smoke and ash from the fires has triggered fire-induced thunderstorms, which provide a pathway for the smoke to travel more than 16 kilometres up into the stratosphere, NASA said.

Lieutenant Kynan Lang from the 10th/27th Battalion visits the scene where his uncle and cousin died in a bushfire to place a memorial on Kangaroo Island, Australia. Reuters Australian Army CH-47 Chinooks from the 5th Aviation Regiment deliver hay bales to remote bushfire-affected farms on Kangaroo Island, Australia. Reuters Melbourne commuters walk wearing a mask as the city suffers hazardous air quality in Melbourne, Australia. Getty Australian Army CH-47 Chinooks from the 5th Aviation Regiment return from delivering hay bales to remote bushfire-affected farms on Kangaroo Island, Australia. Reuters A handout satellite image made available by NASA shows thick smoke moving into the Tasman Sea from the states of New South Wales and Victoria. EPA The West Gate bridge is shrouded in smoke as hazardous air quality and bushfire smoke blankets the city in Melbourne, Australia. Getty Lieutenant Kynan Lang from the 10th/27th Battalion visits the scene where his uncle and cousin died in a bushfire to place a memorial on Kangaroo Island, Australia. Reuters NSW National Parks and Wildlife services dropping carrots and sweet potato over the bushfire affected areas along the South Coast for wallabies. AFP National Parks and Wildlife services loading carrots and sweet potato to drop over the bushfire affected areas along the South Coast for wallabies. AFP A wallabie eating a carrot dropped by the NSW National Parks and Wildlife services over the bushfire affected areas along the South Coast for wallabies. AFP

“Once in the stratosphere, the smoke can travel thousands of miles from its source, affecting atmospheric conditions globally,” it said.

The fires have burned across an area twice the size of Switzerland causing at least 28 deaths and destroying thousands of homes. They have also pumped out more than half of the country’s annual carbon-dioxide emissions in another setback for the fight against climate change.

But hopes of containing Australia's months-long bushfire crisis rose on Tuesday with heavy rain forecast, but toxic smoke in Melbourne disrupted warm-up events for the year's first tennis Grand Slam.

Cool weather over recent days had already given some respite for exhausted firefighters spread out across vast swathes of the country, allowing some of the biggest blazes to be brought under control.

Heavy rain was forecast for some of the hotspots in the most populated eastern states of New South Wales and Victoria.

"It's some pretty good news," New South Wales Rural Fire Service Commissioner Shane Fitzsimmons said.

"We've been talking about it for months now, that January might see the first fall of decent rain, and that looks like what's coming along over the next few days."

The rain was set to begin across eastern Australia on Wednesday and last through the weekend, according to government meteorologist Sarah Scully.

"Hopefully some of this heavy rainfall will fall over some of the fire sites and help control or even extinguish some of those fires," Scully said.

However, dozens of fires remained out of control and, with many weeks of hot weather still expected throughout the rest of Australia's summer, there was no suggestion the crisis would completely end soon.

Toxic smoke from the blazes also blew overnight into the Victorian capital of Melbourne, which is due to stage the Australian Open tennis tournament beginning next week.

Pollution in Melbourne, which is normally ranked as among the world's most liveable cities, was rated "hazardous", and health authorities warned people to stay indoors.

World number one Rafael Nadal and other stars abandoned outdoor practice sessions and hit indoors.

Grace Staberg, of the United States, competes in the women's ski mountaineering during Day 1 of the Lausanne 2020 Winter Youth Olympics on Friday, January 10. Getty Thomas Pieters tees-off on the eleventh during Day 2 of the Abu Dhabi HSBC Championship on Friday, January 17. Getty Manchester City's Sergio Aguero scores his side's fifth goal during their 6-1 win at Aston Villa in the Premier League on Sunday, January 12. PA Stephane Peterhansel and co-driver Paulo Fiuza during Stage 9 of the Dakar Rally, from Wadi Al Dawasir to Haradh in Saudi Arabia. Reuters England batsman Ollie Pope during the first day of the third Test against South Africa in Port Elizabeth on Thursday, January 16. AFP Lebanese skier Ray Iskandar competing in the men's slalom at Les Diablerets Alpine Centre during the 2020 Lausanne Winter Youth Olympic Games, on Tuesday, January 14. AFP Spain's Carolina Marin eyes a return against India's Saina Nehwal during their quarter-final match at the Malaysia Open badminton tournament in Kuala Lumpur on Friday, January 10. AFP Bryce Cotton of the Perth Wildcats dunks during the NBL match against the Illawarra Hawks in Wollongong, Australia, on Friday, January 10. Getty Anna Kay competes in the British Cycling National Cyclo-Cross Championships at Shrewsbury Sports Village, on Sunday, January 12, 2020. AFP Winona Costin, in orange, guides Assault'n'Bathory to victory in The Tab Highway Handicap during Sydney Racing at Royal Randwick Racecourse on Saturday, January 11. Getty Athletes compete in the women's 4000m Speed Skating event at the Lausanne 2020 Winter Youth Olympics on Thursday, January 16. AFP Driver Denis Berezovskiy and co-driver Adrian Torlaschi race their Can-Am during Stage 8 of the Dakar Rally in Saudi Arabia, on Monday, January 13. AP A general view of the city skyline shrouded by smoke haze from bushfires during an Australian Open practise session at Melbourne Park, on Tuesday, January 14. Reuters AC Milan's Zlatan Ibrahimovic warms up prior to their Serie A match at Cagliari on Saturday, January 11. Ibrahimovic would go on to score in a 3-0 win. AP Kseniia Sinitsyna of Russia competes in the women's figure skating during Day 4 of the Lausanne 2020 Winter Youth Olympics. Getty Australia's Steve Smith during a training session ahead of their first one-day international match against India, on Sunday, January 12. AP Justin Harding in a tricky spot during Round 1 of the Abu Dhabi HSBC Golf Championship on Thursday, January 16. EPA Athletes take part in quarter finals of the ski mountaineering women's wprint at the Winter Youth Olympic Games, on Monday January 13. AP Runners and riders during the McCoy Contractors Civil Engineering Classic Handicap Chase at Warwick Racecourse in England, on Saturday, January 11. PA Left to right: Shreyas Iyer, Virat Kohli and Navdeep Saini during a training session on Monday, January 13, ahead of their first ODI against Australia in Mumbai. India lost the match by 10 wickets. AP The Men's speed skating final during Day 7 of the Lausanne 2020 Winter Youth Olympics. Getty Conor McGregor, left, and Donald "Cowboy" Cerrone on Wednesday, January 15, ahead of their welterweight bout at UFC 246 in Las Vegas. AP A Super Rugby pre-season match between the Chiefs and the Blues at Waihi Athletic Rugby Club in New Zealand on Friday, January 17. Getty Polish athlete Marcin Kielbasa during practice for the men's luge at the St Moritz Olympia Bob Run, at the Lausanne 2020 Winter Youth Olympics, on Tuesday, January 14, 2020. AFP Jose Ignacio Cornejo Florino on his Honda motorbike during Stage 11 of the Dakar Rally between Shubaytah and Haradth in Saudi Arabia, on Thursday, January 16. AP Athletes compete in the curling mixed team round robin, during Day 4 of the Lausanne 2020 Winter Youth Olympics on Monday, January 13. Getty Caroline Wozniacki during an Australian Open practice session at Melbourne Park, on Thursday, January 16. EPA Dubai-based amateur Josh Hill practices during Day 2 of the Abu Dhabi HSBC Championship on Friday, January 17. Getty Yu Yangyi, right, of China competes against Russia's Nikita Vitiugov during the 82nd Tata Steel Chess Tournament held at, Philips Stadion, the home of Dutch football club PSV Eindhoven, on Thursday, January 16. Getty Kyla Ross of UCLA competes on beam during a gymnastics meet against Boise State at Pauley Pavilion on Sunday, January 12, 2020 in Los Angeles, California. AFP

But Australian Open qualifying rounds went ahead after a two-hour delay in the morning, causing anger and confusion for some players who said matches should have been cancelled for the day.

Slovenian Dalila Jakupovic, ranked 201 in the world, had to retire from her match after suffering a coughing fit, and she later blamed the smoke.

"I was really scared that I would collapse... it's not healthy for us," she told reporters.

"I was surprised, I thought we would not be playing today but we don't have much choice."

Mandy Minella, the world number 140 from Luxembourg, also voiced her opposition on Twitter.

"Shocked to see that qualifying matches have started @Australian Open, What about the health of all the people that have to work out there, especially the ballkids?" she tweeted.

An exhibition match involving former world number one Maria Sharapova was also called off because of the smoke.

The hazy conditions were not expected to last all week in Melbourne, with a change in wind direction and the forecast wet weather set to clear the city's air by Wednesday night.

However, Tuesday's drama raised concerns about whether the two-week Australian Open, which is often played in extreme heat, could be interrupted by another smoke surge.

Novak Djokovic, president of the ATP players council, had already said last week that the tournament may need to be delayed if the pollution levels were too high.

Organisers have said there is little chance of it being delayed.

The bushfires have killed at least 27 people, destroyed more than 2,000 homes and burnt 100,000 square kilometres of land – an area larger than South Korea or Portugal.

Australia endures bushfires every summer.

However, climate change and a prolonged drought have contributed to the current crisis, with the blazes starting much earlier than normal and lasting for far longer.

Australia experienced its driest and hottest year on record in 2019, with its highest average maximum temperature of 41.9 degrees Celsius recorded in mid-December.

The fires have prompted an outpouring of donations from around the world to help communities and devastated animal populations.

Environmental groups estimate 1 billion animals have been killed, many of them unique to Australia.

The country's environment minister Sussan Ley has warned that in some areas, koalas may have to be reclassified as endangered.