TAIPEI (Taiwan News) -- Due to the arrival of a weather front today (May 20) the Central Weather Bureau (CWB) has issued a heavy rain advisory for 21 of Taiwan's 22 counties and cities.

The CWB predicts that the weather front will bring showers and thunderstorms throughout all of Taiwan proper and most outer islands. Due to the intensification of the northeastern monsoon and heavy rainfall, temperatures in northern Taiwan will become significantly cooler.

The CWB has issued an extremely heavy rain advisory for New Taipei City, Taipei City, Keelung City, Taoyuan City, Miaoli County, Hsinchu County, and Hsinchu City. The CWB has issued a heavy rain advisory for Yilan County, Taichung City, Hualien County, Changhua County, Nantou County, Yunlin County, Chiayi County, Chiayi City, Kaohsiung City, Tainan City, Taitung County, Pingtung County, Kinmen County, and Penghou County.

As for temperatures, the mercury in northern Taiwan will drop from 26 to 27 degrees Celsius during the day to 20 degrees in the evening. In the rest of the country, daytime highs will range between 28 and 30 degrees, while lows will drop to between 22 and 24 degrees.

The CWB warns of strong wind gusts of up to 8 or 9 on the Beaufort scale in northern and eastern Taiwan (Including Orchid Island and Green Island). Meanwhile, the CWB has advised possible flight delays in Kinmen and Matsu due to fog or low clouds.