2 November 2022

Mainly attributed to the stronger than normal subtropical ridge over southern China, October 2022 was sunnier than usual in Hong Kong. The duration of bright sunshine in the month was 241.0 hours, 43.2 hours above normal. The mean maximum temperature of 29.5 degrees and mean temperature of 26.2 degrees were 1.4 degrees and 0.5 degrees above the respective normals and were respectively one of the highest and one of the eighth highest for October on record. The month was also drier than usual with a monthly rainfall of only 49.9 millimetres, about 41 percent of the normal of 120.3 millimetres. The accumulated rainfall this year up to October was 2048.9 millimetres, about 13 percent lower than the normal figure of 2363.1 millimetres for the same period.

Under the influence of a broad trough of low pressure, there were sunny intervals and a few showers in Hong Kong on the first day of the month. With the anticyclone aloft strengthening gradually, showers reduced on 2 October and local weather became generally fine and very hot in the following two days. The maximum temperature at the Observatory rose to 33.5 degrees in the afternoon on 4 October, the highest of the month and also the hottest Chung Yeung Festival on record.

The northeast monsoon reached the coast of Guangdong on 5 October and there were sunny periods and a few showers in Hong Kong on that day. Local weather turned mainly fine during the day on 6 October. Under the influence of another replenishment of the northeast monsoon, there were sunny periods during the day with showers in the morning and at night on 7 October. More than 30 millimetres of rainfall were recorded in Tai Po and Sha Tin. Affected by a fresh to strong northeast monsoon, apart from a few showers, it was generally fine and dry during the day on 8 – 9 October.

With the arrival of a replenishment of the northeast monsoon on 9 October, local winds strengthened from the north that night. It became cooler on 10 October. Local weather remained generally fine and dry on 10 – 16 October under the influence of the dry continental airstream. Meanwhile, an area of low pressure over the seas east of Luzon intensified progressively into a tropical storm on 15 October and was named Nesat. After moving across the Luzon Strait, Nesat entered the northeastern part of the South China Sea and intensified rapidly into a typhoon on 16 October. It moved west-southwestwards across the northern and central parts of the South China Sea in the next two days. Nesat weakened progressively into a tropical storm over the seas south of Hainan Island on 19 October and further degenerated into an area of low pressure in the vicinity of Beibu Wan the next day.

Under the combined effect of the northeast monsoon and Nesat, it was windy in Hong Kong on 17 – 18 October. Local temperatures started to drop appreciably on the early morning of 18 October and the weather became rainy and cool later on that day. The temperature at the Observatory dropped to a minimum of 17.3 degrees on the night of 18 October, the lowest of the month. As Nesat departed from the coast of Guangdong, local weather improved with sunny periods on 19 – 20 October. It was also very dry during the day on 19 October.

An anticyclone aloft brought generally fine and dry weather to Hong Kong on 21 – 22 October. Meanwhile, a tropical depression moved across the Luzon Strait on 21 October and entered the northeastern part of the South China Sea the next day. The tropical depression moved west-southwestwards across the northern part of the South China Sea afterwards and finally weakened into an area of low pressure on 23 October. Affected by the tropical depression and its remnant low pressure area, local weather became cloudier on 23 October. Under the influence of a dry northeast monsoon and its subsequent replenishment, sunny and dry weather persisted on 24 – 30 October.

Meanwhile, an area of low pressure over the seas east of the Philippines intensified progressively into a tropical storm on 27 October and was named Nalgae. It moved west-northwestwards towards Luzon the next day. Nalgae intensified into a severe tropical storm and moved across Luzon on 29 October. It moved north-northwestwards across the central part of the South China Sea the next day. Under the combined effect of Nalgae and the northeast monsoon, the weather of Hong Kong turned cloudier with winds strengthening from the north on the last day of the month.

Eight tropical cyclones occurred over the South China Sea and the western North Pacific in October 2022.

Details of issuance and cancellation of various warnings/signals in the month are summarized in Tables 1.1 to 1.5.  Monthly meteorological figures and departures from normal for October are tabulated in Table 2.