The State Emergency Service has issued 50 flood warnings across New South Wales as heavy downpours drench the state.
So far none have been emergency warnings, but 14 are listed as “watch and act”.
The SES is deploying additional resources and equipment to high risk areas in preparation for increasing heavy rainfall on parts that are already saturated.
Sydney has been warned its “danger day” could be Saturday, with residents in at-risk zones told to start preparing now.
Sydney is having its wettest 12 months in the 164 years records have been kept.
The previous high was set in 1950, when 2194mm was recorded at Observatory Hill — a mark broken just after 1pm today.
Weatherzone said Sydney’s rainfall had been evenly distributed throughout the year.
“This year, with strong contributing influences from climate drivers like La Niña (twice), the heavy rain has barely eased off in any month except June, when just 16.8mm was recorded,” Weatherzone said.
NSW Emergency Services Minister Steph Cooke said the rain in Sydney was only going to get worse.
“Our catchments are saturated, our dams full, and rivers are already swollen so any extra rainfall, no matter how minor, is likely to exacerbate the existing circumstances,” Cooke said.
The Bureau of Meteorology’s Gabriella Woodhouse said it had already observed widespread rain and flash flooding across inland parts of NSW.
“Today we are looking at severe thunderstorms in the very far west of the state, this includes the risk of isolated supercells,” Woodhouse said.
“These storms are quite severe in nature and bring the risk of rain, flash flooding as well as damaging winds and some hail.”
Another weather system is expected to develop on Friday and move across the state on the weekend.
“That’s where we’ll see a low-pressure system form and move off the coast during Saturday and Sunday,” Woodhouse said.
“This system is quite a significant and serious system as we are looking at widespread rain as well as thunderstorms with this system.”