Taipei: A low-pressure system, combined with southwesterly winds, will continue to affect Taiwan on Thursday, bringing a high chance of rain nationwide, according to the Central Weather Administration (CWA). Meanwhile, the CWA has issued extremely heavy rainfall advisories for Changhua, Nantou, Yunlin, Chiayi, and Tainan.According to Focus Taiwan, an extremely heavy rain advisory is issued when rainfall exceeds 200 millimeters in a day or 100 millimeters within three hours. An advisory for extremely torrential rain-defined as over 500 mm of rainfall within 24 hours-is also in effect for Taitung and Pingtung counties in southern and southeastern Taiwan. Unstable weather is also expected to affect Taiwan's offshore islands, including Penghu, Kinmen, and Matsu, with a likelihood of heavy rain, the CWA said.The CWA said temperatures across Taiwan on Thursday are expected to range from highs of 27-31 degrees Celsius to lows of 25-27 degrees. Independent meteorologist Wu Der-rong noted that the unstable weather is likely to persist into Friday due to abundant moisture carried by southwesterly winds.Cloudy to sunny skies are expected across Taiwan over the weekend, though brief afternoon showers may still occur, Wu said, adding that rain is more likely from Monday to Wednesday.