The heavy falls were due to a slow moving storm cell that dumped 80mm of rain over Penrith in just three hours and 114mm in total. These high rain rates produced flash flooding, but only within a 10km radius of Penrith. Nearby, Richmond received just 20mm of rain and the city only gained 4mm.

Elsewhere in the region, heavy storms affected areas around Wollongong. Balgownie gained close to 100mm during the past 24 hours with reports of flooding around the region.

More rain is expected for the Sydney region today and tomorrow with isolated thunderstorms also predicted to return. These storms are likely increase in frequency during the afternoon due to a low pressure trough that is lingering over the east coast of NSW. There is the chance of flash flooding as any storms that develop are likely to be slow moving again.

Sydney's weather is expected to improve on Sunday with some sunny periods developing, however a few late showers will return to the region.