Virgin has cancelled all flights in and out of Bali's Denpasar Airport because of ash from the erupting Mount Raung.

Jetstar said it had cancelled three flights yesterday and one today to Perth and delayed two flights in and out of Melbourne.

The airline's only morning outbound flight from Melbourne to Bali has been delayed from 9.15am to 1.15pm, with an update due later this morning.

Conditions are unsuitable for flying because winds are highly unpredictable and are pushing volcanic ash back towards the airport, Virgin said.

Virgin advised passengers not to go to airports or contact the airline, but wait for updates via the website or SMS messages.

The airline said it planned to schedule additional flights once the conditions improve.

Duty Forecaster at the Volcanic Ash Advisory Centre, Grace Legge, said ash plumes were not blowing over Bali at the moment, but there could be an aviation hazard later today.

"Volcanic ash itself, when it gets into the engine, it can get heated up and actually coat parts of the engine," she said.

"It can become basically large chunks of glass almost.

"So if that goes through an engine it definitely will cause problems for it."

Earlier this month thousands of holidaymakers were stranded when Mt Raung erupted.

Australian carriers Virgin and Jetstar cancelled and delayed numerous flights throughout July, sending extra planes to the holiday island when the ash had cleared to help move 4,000 stranded Australians.

Tourists reported being frustrated with their airlines, with many complaining of poor communication and a lack of information about flights.

Families were also left out of pocket, with some forking out thousands of dollars to cover the cost of new flights and extra accommodation.