Heavy rain, damaging wind, severe thunderstorms and hazardous surf will affect NSW today, prompting multiple warnings across the state. A low pressure system positioned over central NSW this morning will move off the coast and deepen over the Tasman Sea later today. Moisture-laden and blustery onshore winds to the south of the deepening low are likely to cause flash flooding and damaging wind gusts. A severe weather warning was in place this morning for the coast and adjacent ranges of the Illawarra and South Coast districts. Flooding is possible between Bega and Nowra, while damaging wind gusts may occur to the north of about Narooma, mainly during the afternoon and evening. While rain won't be as widespread north of the low, a trough extending across central and northern parts of the state will trigger extensive thunderstorm activity today, some of which will be severe. Sydneysiders slept through another rainy night and woke to rumbles of thunder this morning. Shortly before 8am, a warning was issued as an intense storm moved off the ranges towards southern Sydney and Wollongong. A gauge at Bellambi Point collected 10mm of rain in 10 minutes. Further intense storms will develop over the central and northern slopes, ranges and coast of NSW today, before contracting to the state's northeast in the late afternoon and evening. Rain and storms will affect the Sydney Basin until the afternoon, before drier and windy conditions develop for tonight and Tuesday. Any storms that develop in NSW today have the potential to cause damaging winds and large hail, while heavy rainfall and flooding is also a risk. Some of today's storms will affect areas of northeast NSW that are still recovering from wild weather on Sunday. Ballina had its wettest day in five months yesterday and collected a whopping 91mm of rain in just over an hour early in the evening, including 33mm in 10 minutes. There were also reports of golf ball sized hail in nearby Alstonville and Wollongbar. The low will also produce hazardous surf along the Illawarra and Batemans Coasts today and areas between the Illawarra and Macquarie Coast on Tuesday. The latest warnings are available at: http://www.weatherzone.com.au/warnings.jsp