Sydney BDO a cool and chilled affair

One word defined the 2014 Big Day Out in Sydney: cool.

Cool weather and a cool crowd made it a chilled-out event, with NSW Police reporting festival attendees were well behaved.

"There's been a few intoxicated people ejected and a few drug detections, but nothing major," a police spokeswoman told AAP at 6pm (AEDT) on Sunday.

"The drugs as well were pretty small amounts - just for personal use, no suppliers at this stage," she said.

"The crowd's been very well behaved."

By 3pm, ambulance officials said three people had been hospitalised for intoxication.

The police spokeswoman attributed the crowd's good behaviour to the weather.

"When it's hot, people drink more," she said.

The clouds cleared about 4pm and bathed the Homebush showgrounds in sunshine as US indie pop band Grouplove finished off their set.

It was a change from last year's event, when temperatures of 45C made it the hottest on record.

However, a pressing concern facing attendees were snaking queues for the bars.

One of the festivals' organisers, AJ Maddah, tweeted "Massive f*** you to the incompetent turds at Sydney showground and their public catering. How many attempts do you need to run a good bar?"

This year's line-up attracted a slightly older clientele.

Mudhoney, a flagship band from US grunge label Sub Pop, started gathering the older festival-goers at 4.30pm.

As the crowd numbers grew late in the afternoon, Big Day Out organisers said the expected overall attendance was 35,000.

Energetic Swedish band the Hives warmed up the crowd at the main stage before Liam Gallagher's band Beady Eye brought a more chilled-out presence to the evening.

More people streamed into the main stage area in anticipation of Canadian indie darlings Arcade Fire.

Most of the crowd was expected to stay in the main stage area as festival headliners Pearl Jam played directly after, with the grunge godfathers expected to deliver a two and a half hour set.

Hip-hop artist Snoop Dogg, lined up to play on the Red stage in the same time slot, was more likely to draw a younger audience.

Electronic DJ outfit Major Lazer was to finish off the Big Day Out at 10.45pm.