Woodhouse said more alerts will be issued in the coming hours as the trough continues to develop.
Statewide, five-cent-sized hail was reported near Grafton, while local residents reported pea-sized hail near Lithgow.
SES NSW said locals affected by the weather warning should drive their cars away from trees and stay indoors.
Light rain also began on the first day of the cricket test match between Australia and South Africa at the SCG, but the match had not yet been abandoned.
And after days of glorious sunshine flooded the city, the rain is expected to continue through the end of the week.
“It looks like it’s going to be quite chilly and rainy for the next few days,” Woodhouse said. “We could still see a thunderstorm on Thursday.”
Showers are likely to be any day in Sydney through Saturday when they are expected to ease up for the weekend before returning early next week.
The rain comes after a year of record-breaking rainfall in the state, driven by a combination of climate drivers including La Nina, the Indian Ocean negative dipole (IOD) and the Southern Annular Mode (SAM).
The Bureau of Metrology said Wednesday that the country is still in La Nina but is weakening.
Indicators in the Pacific “have warmed slightly compared to two weeks ago and are moving away from La Nina thresholds,” it said.
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https://www.smh.com.au/environment/weather/severe-weather-warning-issued-as-thunderstorms-begin-to-lash-sydney-20230104-p5cac3.html?ref=rss&utm_medium=rss&utm_source=rss_environment Thunderstorms expected across the city