Weekly Weather Forecast: Good Weather Gone! Enhanced Southwest Winds Bring Heavy Weekend Rains, One Area Faces Torrential Rain, Rain Zones Shift Next Week

Taiwan's weather will become increasingly unstable starting today (14th) through the weekend. Wu Sheng-yu, Senior Advisor at Weather Risk Company, pointed out that southwest winds will gradually strengthen over the next few days, increasing moisture from the sea and significantly raising the chance of rainfall in central and southern Taiwan. Northern regions and mountainous areas should remain alert for afternoon convection. Starting next Monday (17th), wind patterns around Taiwan will shift, with prevailing southwest winds turning to easterly to southeasterly flows, causing the main rainfall zones to relocate.

Weather Forecast: Southwest Winds Push Moisture Inland – Increased Rainfall in Central and Southern Taiwan Over the Weekend

According to Wu Sheng-yu, a low-pressure system over the Yangtze River basin and southern China is moving northeastward and deepening, enhancing southwest winds around Taiwan. With increased moisture, areas south of Taichung will not only face afternoon rains but may also experience scattered showers or thunderstorms at other times. Rainfall will be more pronounced south of Chiayi, with some areas possibly seeing heavier downpours.

Rain bands associated with this southwest flow will penetrate further inland than in the past two days. At night and into the following morning, coastal areas will be affected by land breezes, making convection more likely. During the day, solar heating will again strengthen convection over land, so areas from Chiayi and Nantou northward through Taichung, northern Taiwan, and mountainous Yilan should watch for thunderstorm development in the afternoons.

Afternoon Rains Stronger in Taipei, New Taipei, Keelung, and Yilan – Taipei May Hit 36°C

For lowland areas, Wu highlighted Taipei, New Taipei, Keelung, and Yilan, noting clearer afternoon rainfall signals, with a higher probability of localized heavy thunderstorms in greater Taipei. Those planning outdoor activities, especially in the afternoons, should monitor thunderstorm development closely to avoid sudden, intense downpours.

Despite increased rainfall, temperatures will remain high. From today through the weekend, daytime highs across Taiwan will range from 32 to 34°C. Central and southern regions may see slightly lower temperatures due to more rain, while northern and Hualien-Taitung areas will remain muggy before afternoon thunderstorms. The Taipei Basin could see highs of 35 to 36°C or more from morning to noon.

Weather for the Coming Week: Wind Shift from Monday – Increased Rainfall in Hualien-Taitung and Hengchun Peninsula

Starting next Monday, weather patterns will enter a new phase. Wu analyzed that as the northern low-pressure system driving the southwest winds gradually moves away, the overall low-pressure trough will shift westward. Meanwhile, a new low-pressure circulation will gradually form from the South China Sea to near the Philippines, shifting Taiwan’s relative position from the southern to the northern side of the trough.

Due to this large-scale wind shift, Taiwan’s surrounding winds will change from southwest to easterly to southeasterly. Consequently, central and southern Taiwan will no longer be the primary windward side, and areas more prone to rain will shift to Hualien-Taitung and the Hengchun Peninsula. Western Taiwan will mainly see afternoon thunderstorms as the primary weather change. This unstable pattern may persist until the Pacific high pressure system returns near Taiwan.

Hengchun Peninsula Under Torrential Rain Alert – Short-Term Heavy Rainfall Possible Across Multiple Areas

The Central Weather Administration issued a torrential rain advisory at 4:05 PM on the 14th, expected to last through tonight. The Hengchun Peninsula is included in the torrential rain zone; heavy rain advisories were also issued for Keelung City, the North Coast, Taipei City, New Taipei City, mountainous areas of Taoyuan City, Hsinchu County, Miaoli County, Chiayi City, Chiayi County, Tainan City, Kaohsiung City, Pingtung County, mountainous areas of Yilan County, Taitung County, and Lanyu Island.

According to CWA standards, torrential rain means accumulated rainfall of 200 mm or more in 24 hours, or 100 mm or more in 3 hours; heavy rain means 80 mm or more in 24 hours, or 40 mm or more in one hour. Affected by southwest winds and afternoon convection, some areas may experience short-duration intense rainfall. The public should beware of lightning and strong gusts, mountainous areas should watch for landslides and falling rocks, and low-lying areas should guard against flooding.

What’s Next for the South China Sea Low-Pressure System? Significant Uncertainty Remains

Wu also cautioned that with the shift in the low-pressure trough next week, whether the new low-pressure center forming near the Philippines will continue to intensify remains highly uncertain, with large forecast variability, so it’s too early to make definitive judgments.

Overall, while wind patterns and main rainfall zones will shift from the weekend into next week, unstable weather will persist across Taiwan. Central and southern regions should guard against intermittent showers, while northern and mountainous areas should remain alert for afternoon thunderstorms. Temperatures will remain high when not raining, so carrying rain gear and sun protection is strongly advised when going outdoors.