Revellers heading to Sydney for Saturday's Mardi Gras celebrations no longer face the prospect of wild weather despite wet conditions, according to the Bureau of Meteorology's latest update.

The bureau's 9:48am update on Saturday cancelled a severe weather warning for Sydney, the Hunter and the Central Tablelands advising residents to brace for heavy rain, thunderstorms and possible flash flooding along parts of the coast.

The warning remains in place for people in the South Coast and parts of the Illawarra, Southern Tablelands and Snowy Mountains districts.

Areas of the Illawarra and South Coast have recorded falls of more than 100mm over the past 24 hours as a low pressure system off the state's central coast drifts south and southeast.

Moruya, south of Bateman's Bay, soaked up 134mm in the 24 hours to 9am Saturday. St Albans in the Hunter was drenched with 124mm of rain, while Brooman, inland of Ulladalla, received 118mm.

Moruya River valley is under flood watch, the bureau advised.

Meteorologist Zach Porter said conditions across Sydney were expected to improve slightly ahead of Saturday evening's Gay and Lesbian Mardi Gras Parade.

"On the radar, we can see the shower activity has already eased substantially," he said.

"There will still be a few showers around tonight but the threat of heavy rainfall has passed for Sydney, so falls will be lighter and less frequent."

The forecast remains much the same for the coming week, Mr Porter said.

"It looks like showers will be sticking around Sydney throughout the week and into Friday."

At Sydney Airport, operations are running smoothly again for the wild weather forced six flights to be cancelled on Friday evening, including flights from the Gold Coast and Melbourne.