A poncho or a raincoat is probably not the pinnacle of Mardi Gras fashion, but forecasters recommend partygoers dress for the wet tonight because it seems likely to rain on the parade.
It has rained on March 1 for the past five years, and Saturday's weather will continue on the tradition.
Showers and heavy rain were predicted for the rest of day across Sydney, although there was some chance of it easing briefly around 7pm, said Ben McBurney, a meteorologist at Weatherzone.
But from 8pm to 11pm, when the Mardi Gras floats move along Oxford Street Darlinghurst, rain was expected to return, said Mr McBurney.
The evening was expected to be cool, with temperatures in the high teens when the parade starts.
Mr McBurney said rain was typical for March, which was usually Sydney's second wettest month after June.
The 35th Mardi Gras Parade tonight was expected to go on as it has done through many downpours over the years, including 2012, 2004 and 1995.
Children's sporting finals and semifinals culminating the summer season were washed out across Sydney, with particularly heavy rain on the North Shore and Northern Beaches.
The Lindfield Cricket Club's under 12s teams were washed out of their semi finals at St Ives, dashing the boys' hopes of making it into the grandfinals.
"The wet weather made it impossible for the U12 medium pace bowlers to emulate the reverse-swing that destroyed the National team recently," joked one of the team's coaches Nick Malik. ''And a soggy ball is no fun for the next-gen Warnies attempting to perfect their wrong-uns.''
In the 24 hours to 9am on Saturday, 21mm of rain fell in Terrey Hills, and 20mm in Frenchs Forest.
That compares with a total of 58 mm of rain -- about half the longterm average --- in Sydney in all of February, said Mr McBurney.
It was the driest February since 2011, ending the driest summer in 27 years.
Weatherzone.com.au is owned by Fairfax Media, publisher of The Sydney Morning Herald.