Sydney, April 2 : The wild weather that has buffeted east of Australia for weeks is continuing with gale-force winds expected along the coast of the state of New South Wales (NSW), including the nation's largest city of Sydney. The destructive gusts, which are predicted to exceed more than 100 km per hour, are being caused by an intense low-pressure system moving south, Xinhua news agency reported. The extreme system has already caused flooding, for the second time within a month, throughout the northern regions of NSW, with more than 21,000 people still under evacuation orders. Sydney's predicted blustery conditions followed a turbulent night with powerful winds having torn off the roof of a three-storey building near the CBD in the early hours of Friday, leading to the evacuation of 10 people. Meanwhile, NSW State Emergency Service (NSW SES) received 650 calls for help throughout the past 24 hours as trees were toppled, and power lines were felled. "Keep at least eight metres away from fallen power lines or objects that may be energised, such as fences," the NSW SES said in a statement on Friday. Authorities have also issued warnings against swimming, fishing, or boating due to hazardous surf including high tides, huge swells and waves which are expected to exceed five metres in height. "Boaters planning to cross shallow water and ocean bars should consider changing or delaying their voyage," the NSW Police Force Marine Area Command advised in a statement. The punishing conditions could also trigger coastal erosion, according to the Bureau of Meteorology, and owners of beachfront homes have subsequently been put on alert ahead of the pounding waves and strong winds. Sydney can expect about another 25mm of rain throughout Friday, adding to the drenching it received throughout the previous month. The deluges, which totalled about 540mm, was the most rainfall ever recorded for a March since meteorology records began in Sydney in 1859, and, overall it was the sixth wettest ever month for the city. /IANS