A wet October
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Affected by a strong easterly airstream, the weather of Hong Kong was mainly cloudy with sunny periods on the first day of the month. Affected by an anticyclone aloft, it was generally fine from October 2 to 4. With plenty of sunshine, the maximum temperature at the Hong Kong Observatory soared to 31.9 degrees on October 3, the highest of the month. A cold front moved across the coastal areas of Guangdong on the morning of October 5, bringing heavy rain and squally thunderstorms to Hong Kong. More than 50 millimetres of rainfall were recorded over many places in Kowloon and the rainfall recorded at the Hong Kong Observatory even exceeded 100 millimetres. The heavy downpour necessitated the issuance of the Red Rainstorm Warning in that morning.
Under the influence of a fresh to strong northeast monsoon, the weather of Hong Kong was mainly cloudy and slightly cooler from October 6 to 7. A dry northeast monsoon made local weather become generally fine and dry during the day from October 8 to 12. Meanwhile, an area of low pressure gradually developed into a tropical depression over the central part of the South China Sea on the afternoon of October 11 and was later named Nangka. Nangka moved generally west-northwestward across the northern part of the South China Sea and intensified into a tropical storm on October 12. Nangka moved across Hainan Island on the night of October 13 and entered Beibu Wan in the small hours the next day. Nangka made landfall over Vietnam on the evening of October 14 and weakened gradually into an area of low pressure over the Indochina Peninsula the next morning.
Affected by the outer rainbands of Nangka, the weather of Hong Kong turned cloudy with a few rain patches on the night of October 12. Rainy weather persisted on October 13. Under the combined effect of Nangka and the northeast monsoon, local winds strengthened during the day with gale force winds over offshore waters and on high ground. The Gale or Storm Signal No. 8 was issued in the early morning of that day. With the departure of Nangka, the strong northeast monsoon continued to bring windy weather with a few rain patches to Hong Kong the next day.
Dominated by a dry northeast monsoon, apart from a few rain patches during the night from October 16 to 18, the weather of Hong Kong was generally fine and dry during the day from October 15 to 22 with slightly cooler weather from October 17 to 21. The temperature at the Hong Kong Observatory dropped to a minimum of 21.7 degrees on October 21, the lowest of the month. Meanwhile, an area of low pressure gradually developed into a tropical depression over the seas east of the Philippines on October 19 and was later named Saudel. It moved across Luzon on the night of October 20 and entered the central part of the South China Sea the next morning. Saudel moved across the central part of the South China Sea and intensified gradually into a typhoon on the afternoon of October 22. It continued to move generally westwards across the central part of the South China Sea and weakened into an area of low pressure over the seas east of the central part of Vietnam on the morning of October 26.
Affected by the cloud bands associated with Saudel and a dry northeast monsoon, local weather remained dry but also became cloudier and slightly cooler from October 23 to 24. After the weakening of Saudel, the dry northeast monsoon brought generally fine, windy and dry weather to the territory in the next few days. Meanwhile, tropical cyclone Molave moved across the southern and central parts of the South China Sea from October 26 to 28. Under the influence of the moisture spreading from Molave and a strong northeast monsoon, the weather of Hong Kong turned cloudier again with a few rain patches but remained windy from October 28 to 29. With the dissipation of the rainband over the south China coastal areas, local weather became mainly fine towards the end of the month.
Seven tropical cyclones occurred over the South China Sea and the western North Pacific in October 2020.
Details of issuance and cancellation of various warnings/signals in October are summarised in Table 1. Monthly meteorological figures and departures from normal for October are tabulated in Table 2.
Ends/Tuesday, November 3, 2020
Issued at HKT 16:25
Issued at HKT 16:25
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