Clouds clearing for Sydney fireworks

Clear skies and light winds are expected in Sydney as over one million revellers gather by the harbour to usher in 2012.

Morning showers have fallen on Sydney but the Bureau of Meteorology (BoM) is expecting the clouds to clear during the afternoon as temperatures hit a balmy maximum of 25C.

BoM duty forecaster Chris Webb said there was a "pretty good chance" only one of two small cloud puffs would be visible by nightfall.

"It looks good," he told AAP.

"We're expecting clear skies for the evening. It will be gradually decreasing."

He added that light winds were likely for New Year's Eve, with summer's usual strong northeasterly winds unlikely to disrupt the pyrotechnics display.

Cloud-shaped fireworks will form a central part of this year's celebrations, along with butterflies and strobing waterfalls as part of the Time to Dream theme.

The celebrations will also be a time to behave, with Sydney councils banning alcohol from more than 40 popular vantage points.

Police are deploying 2800 officers to target boozing revellers in central Sydney and harbourside dry zones.