By 1.30pm on Thursday the rain gauge at Sydney's Observatory Hill had passed 2200 millimetres recorded this year, breaking the annual rainfall record of 2194mm set in 1950.
With almost three months remaining in 2022 and a third consecutive La Nina declared, further falls mean the new record will be much higher.
After days of driving rain and flooding in inland NSW, a powerful storm system is tracking east with Sydney in for a "dangerous day" on Saturday, NSW Emergency Services Minister Steph Cooke said.
"We know that our catchments are saturated," she said on Thursday.
"The dams are full and our rivers are already swollen so any extra rainfall - no matter how minor - is likely to exacerbate existing flooding circumstances."
The ongoing deluge will see an elevated flood risk in the coming days across inland and eastern NSW, Gabrielle Woodhouse from the Bureau of Meteorology said.
Over the last few days, parts of NSW had already been hit with double to triple the amount of rain they would usually see in a month, she said.
Thunderstorms with some isolated supercells are expected in the state's far west on Thursday, bringing the risk of heavy rain, flash flooding, damaging winds and hail.
On Friday, a trough and cold front will move across NSW before a low pressure system forms off the coast on Saturday and Sunday, bringing an increase in rain, wind and waves to the Illawarra and Hunter regions.
Renewed and prolonged flooding is continuing in inland NSW at the rivers Namoi, Macquarie, Bogan, Lachlan, Murrumbidgee, Murray, Edward, Culgoa, Birrie, Bokhara, Warrego, Paroo, Barwon and Darling.
Catchments including the Hunter, Hawkesbury and Colo rivers and Wollombi Brook are being monitored with further rises expected on Thursday.
Minor flooding is predicted on Thursday in western Sydney's Hawkesbury-Nepean region including in Menangle and parts of Penrith.
Residents are being warned that renewed flooding can present different challenges, especially to inland communities.
"This particular event on saturated ground means that things can happen very quickly," SES Commissioner Carlene York said.
"Don't assume you will get a warning ... it may go straight to an evacuation order."
The Bathurst 1000 is also causing headaches for authorities, with tens of thousands of motorsport fans set to gather at Mount Panorama on the last weekend of school holidays.
"Please don't race to the races," Acting Deputy Police Commissioner Peter Cotter said.
Drivers should be patient and understand they will face delays as some roads will be flooded.
Farmers are concerned the latest deluge will destroy another crop and graziers have been warned to shelter lambs and sheep as temperatures plunge in the Illawarra, South Coast, Southern Tablelands, South West Slopes, Snowy Mountains and ACT regions.
26°C