Australia's east coast braces for weekend washout as freak weather event brings more than a month's worth of rain

Australia's east coast is bracing for a weekend washout with Sydney set to be hammered with more than a month's worth of rain in just 48 hours.

The Harbour City will be lashed with more than 100mm of rain between Friday and Sunday with the miserable conditions expected to last a fortnight. 

Forecasters at Weatherzone said the washout followed a prolonged period of rainfall  generated by a trough on the NSW coast and began on Tuesday. 

Rain is forecast every day from now until the weekend, with the heaviest falls in NSW expected between Saturday and next Tuesday. 

An upper-level low approaching the state will bring widespread falls of 60mm to 120mm to the central and northern NSW coasts and Sydney. 

Isolated falls could exceed 200mm in some areas.

Weatherzone said the largest daily totals are expected across the central and northeastern NSW and southern Queensland on Saturday. 

Some high rain totals are also forecast for NSW's west. 

On Sunday and Monday, the heavy rain will focus on eastern NSW and southeastern Queensland with the heaviest falls along the central and northern NSW coastline. 

Falls between 20mm and 50mm for Sydney is possible for Saturday and Sunday with weekly totals exceeding 150mm and the Central Coast. 

Up to 30mm of rain is forecast for Monday and 20mm on Tuesday.  

Parts of NSW and southern Queensland are expected to flood during this period due to the wet days that have preceded the deluge.

Significant rainfall totals have already been recorded across NSW. 

Nord's Wharf Oval in NSW's Hunter Valley recorded 93mm of rain in the 24 hours leading up to 9am on Wednesday. 

Cooranbong, a town in NSW's Lake Macquarie, recorded its wettest day in 13 years with 52.4mm falling during the same period. 

Norah Head on the NSW Central Coast has been lashed with almost 100mm over the 48 hours to Thursday morning. 

Less than 30km away, Gosford recorded 70mm in the same period.

Thursday will be a drier day in Sydney with just 3mm of rain before totals ramp up to 25mm on Friday and between 20mm and 50mm on the weekend.

Temperatures will struggle to get over 20C this week with minimums of 14C.

Elsewhere across the country, Perth will receive a morning shower on Friday while Melbourne will remain cold and cloudy for most of the week. 

Canberra will get down to 2C on Friday with a maximum of 18C on Sunday while Adelaide can expect blue skies with tops of 20C. 

Brisbane will be plagued by sporadic showers all weekend with tops of 24C, Hobart will remain cold and cloudy and Darwin will be mostly sunny with highs of 35C.