A large volcanic eruption in Bali appears imminent with the Bureau of Meteorology warning the threat of Mount Agung erupting is "high".
Flights out of Denpasar and Lombok airports were grounded for three days as a tropical cyclone pushed large ash plumes into the direct path of Australian flights.
Indonesian experts are still warning of an "imminent" eruption, which could occur anywhere from a matter of hours to the coming days.
Despite this, Denpasar airport announced it would reopen on Wednesday afternoon, Bali time.
Airport spokesman Arie Ahsannurohim said the volcanic ash had drifted south and southeast, leaving clean space above the airport for planes to land and take off.
The closures devastated thousands of travellers, who said they were missing important life events at home including graduations, the funerals of loved ones or new jobs.
On Wednesday, it was estimated 120,000 travellers had been affected by the volcano.
Some desperate to get home have taken a 13-hour bus and ferry ride to Surabaya Airport, in Indonesia's second-biggest city.
Many schoolies celebrating the end of their studies have also been caught up in the natural disaster.
Taylah Kark from Sydney said she and partner Karl Cleary were due to fly home on Tuesday ahead of Karl's grandfather's funeral and him starting a new job.
"Now he can't [start] until we get back and he is scared they're going to be angry with him," Taylah said.
"His grandfather also passed away and we're hoping we don't miss his funeral."
Mount Agung has demonstrated increased seismic activity for the past two months before it began belching out plumes of ash last Tuesday, its first eruption in more than 50 years.
Volcanic ash has also been detected up to seven kilometres in the skies above the summit of Agung, which is 72 kilometres from the popular holiday destination of Kuta.
Thermal anomalies detected on Tuesday evening by NASA, accompanied by reports of a 30-minute tremor inside the crater, showed a "significant" amount of magma welling in the volcano.
On Wednesday afternoon, the Bureau of Meteorology issued an alert, warning "the potential for a larger eruption of Bali's Mount Agung volcano is now high".
Victorian schoolies Jesse Williams and Connor Harvey said they were worried about not being able to come home but wouldn't let the volcano spoil their holiday plans.
"We're a bit worried about the volcano erupting, about our flight back, not about our safety here," Connor said.
"We're fine here. We're just gonna hang around Kuta, Seminyak."
More than 100,000 residents within the 10-kilometre exclusion zone were ordered to evacuate on Monday.
Indonesian authorities are preparing to evacuate 60,000 by force after only 40,000 Balinese heeded the warnings.
The volcano last erupted in 1963, killing more than 1000 people and razing several villages.
Qantas, Jetstar, Virgin Australia and Air Asia cancelled all flights in and out of Bali on Wednesday as ash blanketed Denpasar Airport.
Jetstar confirmed it will be running four extra flights on Thursday carrying about 1000 stranded passengers from Bali as the ash clouds from Mount Agung continues to ground planes.
An airline spokesman said the relief flights would be on top of nine other scheduled flights out of the island destination with Qantas operating a scheduled flight and an extra one.
Jetstar warned, however, that volcanic activity and ash cloud were unpredictable and flights might be cancelled at short notice.
"Our senior pilots will make further assessment tonight and tomorrow morning based on the latest information from the Volcanic Ash Advisory Centre," the spokesperson said.
"We will provide customers further updates if the situation changes."
About 3800 people booked with Jetstar and Qantas will be able to return to Australia.
Flights for tourists travelling to Bali will remain cancelled.
A tropical cyclone off the coast of Java is also altering the path of ash, sending it closer to Denpasar Airport and Bali's popular beaches.
Bali, famous for its surf, beaches and temples, attracted nearly five million visitors last year but business has slumped in areas around the volcano since September when Agung's volcanic tremors began to increase.
with Amilia Rosa, Reuters
Data from @NASA Aura satellite shows high SO2 concentrations from Mount #Agung yesterday in #Bali, #Indonesia. People on the ground witnessing the #volcano emitting thick ash clouds and glowing lava. More satellite imagery: https://t.co/oVYhIsjXNxpic.twitter.com/U3wPxQtfHc??? NOAA Satellites (@NOAASatellites) November 28, 2017
Confusion after 17hrs coach travel from Bali to Surabaya we arrive at 2am to no officials, and with AirAsia refusing to answer all their comms channels there's a lot of people here who have not received a rebooking confirmation and have no idea if they're on tomorrow's flights?!??? Jakob Aungiers (@JakobAungiers) November 28, 2017
Made it onto a plane! Current travel delay time: 54hrs. Then I need to hope that @AirAsiaSupport managed to rebook my flight from KUL - OOL which they hadn't for this morning's flight... I also think #AirAsia need to find a new slogan for their planes! #bali#agung#balivolcanopic.twitter.com/QdAEmOIUmJ??? Jakob Aungiers (@JakobAungiers) November 29, 2017