A pool of unstable cold air in the region whipped up some winter thunderstorms this afternoon and into the evening.

The Bureau of Meteorology this afternoon warned moderate to severe thunderstorms were forecast for parts of the Central Coast, Sydney and the south coast, including Newcastle and Wollongong.

Isolated storms were expected across central and eastern NSW, before spreading “erratically” across the state and towards the coast.

Impacted areas were warned to brace for heavy downpours, hail and strong wind as the storm “packs a punch”, according to Weatherzone.

The bureau, which cancelled the last of its thunderstorm warnings just before 7.30pm, said two-centimetre hail was recorded at Mudgee, about 100 kilometres south-east of Mudgee.

The unstable cold air may bring cumulonimbus clouds, which are characteristic of heavy thunderstorms more common in summer.

Conditions are expected to settle tomorrow, with the stormy weather forecast across the border into Victoria and South Australia.

The deep low over the southern ocean could bring storms on Tuesday and Wednesday in south and central parts of SA and Victoria.

Fights were grounded, some homes were evacuated and thousands lost power.

The city will return to pleasant winter weather by Tuesday, with higher temperatures reaching 18 degrees forecast for Thursday and Friday.