Dykes on Bikes - one of Australia's oldest LGBTQI groups - will kick off Sydney's 2017 Mardi Gras parade, which is expected to draw up to 300,000 revellers.
The Gay Nomads, Australian Marriage Equality, LGBTQI+ Youth and dozens of other floats will follow during the annual, sparkle-filled show of gay pride and equality in Oxford Street's party precinct from 7.30pm.
Up to 12, 000 people will march in the parade, including Peter de Waal and his partner Peter Bonsall-Boone who last year celebrated their 50-year anniversary.
"We have been in the parade many times. Over the years we have been a part of various causes we felt strongly about and we represented those causes in the parade," said Mr de Waal.
"Marriage equality has been a cause close to our hearts for almost half a century."
The large crowds will be matched with a 1000-strong police presence.
Acting Commissioner Superintendent Tony Crandell says the use of vehicles as weapons in Nice and Melbourne has changed the context of policing large gatherings.
"We have certainly considered all of those threats," he said.
The police strategy includes barricades, mounted and aerial units, the dog squad, crowd control specialists and tactical officers.
Supt Crandell also pointed to the massacre at a gay nightclub in Orlando, Florida, as having influenced the "world situation".
Drug and alcohol use will also be heavily policed.
NSW Ambulance deputy commander Wayne McKenna said a strong contingent of paramedics would be on hand to help anyone requiring treatment, but warned revellers to think about safety.
"Be aware that mixing drugs - with or without alcohol - could be lethal," he said.
Malcolm Turnbull, who became the first sitting prime minister to attend the celebrations last year, will not be attending this year's parade.
He said he remains a strong supporter of the event.
"I go most years," he told reporters in Queensland.
Equality has always been central to the philosophy of Mardi Gras, but that message goes beyond marriage equality, says Mardi Gras chief executive Terese Casu.
Ms Casu says she is "praying to the glitter gods" for good weather, with forecasts showers threatening to dampen the parade.
