Hundreds of thousands of revellers are expected celebrate on the streets of Sydney to mark the 39th annual Mardi Gras Parade, and police say they are taking every precaution to ensure the event runs safely and smoothly.

NSW Police said they had considered recent global events, including the Orlando gay nightclub massacre, while planning for this year's festivities.

Despite the rigorous preparation, NSW Acting Assisting Commissioner Tony Crandall insists there is no direct threat to partygoers but that does not mean they are taking any chances.

"Nevertheless we operate on the basis there is [a threat] and we make sure that all of our police resources are in place to make sure that everyone is kept safe and secure," Commissioner Crandall told reporters.

Police launched Operation Rothbury on Friday, which will include more than 1,000 police officers deployed across public transport, roads, and in the air during the event.

"I can assure you that we have considered all sorts of risks, all sorts of threats and that we have strategies in place to mitigate those threats," he said.

Last year's parade drew more than 200,000 revellers into the CBD.

Michael Goode and Ethan Carter are performers on an Andy Warhol tribute float and Wonder Woman-inspired float. ( ABC News: Nour Haydar )

Police said their main priority was crowd safety along the parade route but to also allow them to enjoy the event.

"Every single police officer in this operation is charged with one major mission and that is to keep everybody safe and secure," he said.

"We are not the fun police."

Grim weather: 'It's not going to rain on our parade'

With more than two tonnes of glitter used across 184 floats, event organisers say the parade will shine regardless of the rain that is forecast.

"Rain doesn't really wash glitter away, nothing washes glitter away," Sydney Mardi Gras creative director Greg Clarke said.

"It's not going to rain on our parade, and if it does a little bit it's going to be fine."

Mardi Gras CEO Teresa Casu said the parade will run 30 minutes shorter than last year to cater for the wet weather.

"We have never stopped a Mardi Gras parade in the history of Mardi Gras so it would have to be a pretty torrential hurricane that would stop those floats," she said.

"We are praying to the glitter gods."