A fierce blast of winter has prompted a severe weather warning for most of southern NSW, including Sydney.

Coogee Beach looked like a construction site - or a popular holiday destination for heavy machinery - as 12 large earth movers, two vacuum trucks and a crew of 35 worked to restore the beach to its pre-storm glory.

Sydney in for scorching weather on Friday as a slow-moving high-pressure system steers a huge hot air mass formed over Australia's Red Centre to the country's south-east.

Sydneysiders can expect several days of rain-soaked commutes after an early morning downpour ended three weeks of uninterrupted sunshine.

A powerful cold front is set to bring 'dangerous' conditions to large parts of south-eastern Australia in coming days and send temperatures plummeting in Sydney.