Heavy rain and flooding will target the south coast of New South Wales this weekend, following a wet week further north. Daily showers and thunderstorms have brought more than 100mm of rain to parts of the state's central and northern coasts during the past seven days. Sydney has just experienced its wettest week since last winter after receiving more than 130mm since Saturday. This is about a month's worth of rain for the city at this time of year. Further north, Evans Head collected 221mm between Sunday night and Wednesday morning, making this their wettest week since June last year. While most areas of eastern New South Wales are still seeing showers today, the heaviest falls will occur along the southern half of the coast during the next few days. This is thanks to a low pressure system that is expected to develop off the central coast later today and move south on the weekend. A severe weather warning was issued this morning for the coast and adjacent ranges south of Wollongong, where heavy rain may cause flash flooding today and on Saturday. Showers will also affect Sydney on both of these days as well. In addition to the risk of flash flooding, minor riverine flooding is possible in the Moruya, Bega and St Georges river valleys from Saturday. A Flood Watch has been issued for these areas. The low will also cause wind and wave heights to increase along the state's southern coastline this weekend. There is some uncertainty regarding the movement and intensity of the low from Sunday, although showers are likely to continue along the south coast and may still be heavy at times.