Heavy rains and several low-pressure systems are expected to cause minor to moderate flooding or flash flooding sometime today (Friday) or over the weekend.

Last night 28.4 millimetres of rain fell on Eden with around 18mm falling since 9am.

So far roads and bridges remain open however drivers are urged to drive to the conditions.

In preparation for increased calls for assistance, State Emergency Services Bega headquarters has rostered extra personnel and have helicopters on standby in Bega and at Moruya.

Unit controller John Lacey said extra personnel included seven Eden volunteers and 14 from Wollongong, Shellharbour and Ulladulla.

Last night western Sydney's Penrith region issued 285 calls for help with 38 people, 150 greyhounds and two goats evacuated.

A Bureau of Meteorology spokesperson said people living on flood plains or near riverbanks should be vigilant during the coming days.

"Minor flooding means water will fill up the banks and create good flow but moderate flooding means a bit more trouble," he said.

"It may cut off low level roads and bridges and perhaps interfere with stock.

"Anyone down on flood plains should be on watch for something coming over the next few days."

In Eden, Bega Valley Shire Council staff are keeping a close eye on Lake Curalo.

Eden town team leader Marty King said the lake would be opened with heavy machinery if levels rose to 1.2 metres.

"Legally we can't open it until its 1.2 high on the gauge at Lakeside Drive," he said.

"It can rise pretty quickly, at 1.3 or 1.4 it starts to threaten homes and the sewage pump house."

"At 1.1 I ring Billy (Michelin from J Michelin and Son) and he gets going pretty quick."

SES will issue another update at midday.

For life threatening emergencies, call 000 immediately.

For emergency assistance call the SES on telephone number 132 500.

FloodSafe advice to help you prepare is available at www.ses.nsw.gov.au

For the latest weather forecast see www.bom.gov.au/nsw/forecasts/

Roads and traffic information livetraffic.rta.nsw.gov.au/deskto p.html