Overview of Tropical Cyclone in December 2025

Three tropical cyclones occurred over the western North Pacific and the South China Sea in December 2025.

Koto (2527) formed as a tropical depression over the seas east of the southern part of the Philippines about 970 km southeast of Manila on the morning of 24 November, and moved west-northwestwards across the central and southern parts of the Philippines that afternoon and the next day. It entered the southern part of the South China Sea on 26 November, progressively intensified into a typhoon and attained its peak intensity on the morning of 27 November, with an estimated maximum sustained wind of 130 km/h near its centre. Koto lingered over the central and southern parts of the South China Sea and gradually weakened in the following three days. It finally degenerated into an area of low pressure over the southern part of the South China Sea in the small hours of 3 December.

According to press reports, there were at least two missing, eight injuries and over 930 000 people affected during the passage of Koto in the Philippines. About 500 houses were damaged, and economic loss exceed PHP 18 million.

Senyar formed as a tropical depression over the Strait of Malacca about 270 km west-northwest of Kuala Lumpur on the morning of 25 November. According to the Indian Meteorological Department's Regional Specialised Meteorological Centre New Delhi, this is the first time a tropical cyclone has formed in the region since 1886. Senyar moved westwards that day, and intensified into a tropical storm that night, attaining its peak intensity with an estimated maximum sustained wind of 65 km/h near its centre. Senyar turned to track southeastwards, skirted past the coastal areas of the northeastern part of Sumatra, and weakened into a tropical depression on 26 November. It moved eastwards across the Strait of Malacca again the next day. After making landfall and degenerating into an area of low pressure over the Malay Peninsula on 28 November, it turned northeastwards and moved to the sea again. It re-intensified into a tropical depression that night. Senyar continued its northeasterly track in the following two days. It finally degenerated into an area of low pressure over the southern part of the South China Sea on the morning of 1 December.

According to press reports, Senyar brought torrential rain to Sumatra of Indonesia, the southern part of Thailand, and the Malay Peninsula. Maximum daily rainfall of 411 millimetres and accumulated rainfall of 714.5 millimetres were recorded in Aceh Province, Sumatra between 26 and 27 November. The torrential rain caused widespread flooding and landslides, resulting in at least 1 204 deaths in Indonesia, 276 deaths in Thailand and three deaths in Malaysia. A total of over four million people were affected. Estimated economic losses in Indonesia and Thailand exceeded IDR 68 trillion and THB 500 billion respectively.

A tropical depression formed over the western North Pacific about 1 140 km east-southeast of Manila on the morning of 4 December, with an estimated maximum sustained wind of 45 km/h near its centre, and then moved westwards. It moved across the central part of the Philippines from the night of 6 December to 7 December. It finally degenerated into an area of low pressure over the Sulu Sea in the small hours of 8 December.

According to press reports, the tropical depression and the northeast monsoon brought heavy rain to the Philippines, causing at least one missing and affecting over 710 000 people.