This year is officially Sydney’s wettest on record after yet another downpour over the weather station in the CBD where data is gathered.
A total of 2,199.8 millimetres of rain has been recorded at Observatory Hill in the year to 1.10pm today.
Sydney’s previous rainfall record was set in 1950, when 2,194.0mm was dumped over the city.
Weather records have been kept at Observatory Hill since 1858.
Milton Speer, a meteorologist from the University of Technology Sydney, said the year's record rains stemmed from weather systems staying in place for longer than usual.
Dr Speer said a series of east coast lows and troughs coupled with higher than average sea level temperatures produced persistent rain through March and April.
Then, in July, Sydney received a record downpour for the month thanks to those same conditions.
He said there were some key similarities and differences between 2022's conditions and those of 1950 — which both featured "strong" La Niña systems.
"In 1950, there was record rainfall in June — 10 times the June average — which was the main cause of the record rainfall for that year," Dr Speer said.
"In the early months of the year it only average or just above average rainfall.
"This year there was persistent rain in March and early April ... while July produced a record rainfall this year."
He said it's hard to predict if Sydneysiders can expect more wet years in the near future, as "accelerated climate change" is moving where the troughs and lows which drive rainfall are forming.
But Dr Speer said if current conditions continued the city was set for a rainy summer.
A band of heavy rain is currently sitting over the eastern part of Sydney but is predicted to move off the coast later this afternoon, bringing a short-term reprieve.
However, another band of heavy rain is brewing and intense downpours are predicted over the weekend, with Saturday set to bring the most dangerous conditions.
Some locations across the state are expected to see well over 100mm of rain between now and Sunday night.
Catchments are already saturated and dams are full, with flood warnings for most rivers across the state.
The Bureau of Meteorology's (BOM) Gabrielle Woodhouse said the riverine and flash flooding risk over the weekend was "significant", particularly along the coast.
"[The system coming] is quite a significant and serious system," she said.
"And the flooding we’re looking at looks as though its going to be more significant than what we have have been seeing over the last 12 months."
Ms Woodhouse said there will also be a severe thunderstorm risk in the far west, with possible super cells, and major flooding expected across the Western Slopes.
“These storms are quite severe in nature and they can bring the risk of heavy rain, flash flooding, damaging winds and hail.”
She said that system would move off the coast by Sunday.
Eastern Australia is currently enduring its third La Niña in a row, which brings wetter than average conditions.
Having two La Niñas in a row is common but three is far more unusual and climate scientists have warned people to prepare for the worst this summer.
Sydney has been saturated all year due to La Niña events and back in March the Harbour City had already seen 70 per cent of the average rainfall.
There have been several flood emergencies this year, with residents in the Hawkesbury-Nepean forced to evacuate four times.
