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The weather of October 2015 was warmer than usual. The monthly mean temperature of 26.0 degrees was 0.5 degrees above the normal figure of 25.5 degrees. The month was also wetter than usual, mainly as a result of heavy rain brought by tropical cyclone Mujigae during the first week of the month. A total of 168.3 millimetres of rainfall was recorded in the month, about 67 per cent above the normal figure of 100.9 millimetres. However, the accumulated rainfall of 1 776.3 millimetres since January this year was still about 24 per cent below the normal figure of 2 334.0 millimetres for the same period.
The weather in Hong Kong was cloudy with a few showers and isolated thunderstorms on the first day of the month. Under the influence of the northeast monsoon, there were sunny periods and a few showers the next day. Meanwhile, the tropical depression near the Philippines intensified into a tropical storm named Mujigae while moving into the South China Sea in the morning of October 2. Moving west-northwestwards steadily, it edged closer to western Guangdong and continued to intensify in the next two days. Mujigae developed into a severe typhoon in the small hours of October 4.
Locally, east to northeasterly winds strengthened significantly and the weather also deteriorated with heavy squally showers and isolated thunderstorms in the afternoon on October 3. With Mujigae making landfall near Zhanjiang in Guangdong and weakening gradually in the afternoon of October 4, local winds started to subside gradually. Under the influence of the outer rainbands of Mujigae, there were occasional heavy squally showers and thunderstorms in Hong Kong on October 4 and 5. In particular, more than 40 millimetres of rainfall were recorded over most parts of the territory and rainfall over the western part of Lantau Island even exceeded 100 millimetres on October 4.
Affected by the cloud bands associated with the northeast monsoon, it remained cloudy and showery on October 6 and 7. There was also a localised heavy downpour in the eastern part of the New Territories with more than 150 millimetres of rain falling over Sai Kung in the morning of October 7. Under the influence of a continental airstream, the clouds thinned out with sunny periods in Hong Kong on October 8 and 9. With the strengthening of the northeast monsoon, it became windy with a few rain patches on October 10. The weather became appreciably cooler in the morning of October 11 with temperatures at the Hong Kong Observatory falling to a minimum of 18.5 degrees, the lowest of the month. The weather remained cloudy on the next day.
Dominated by a relatively dry northeast monsoon, the weather in Hong Kong became fine on October 13 and remained generally fine and dry for the ensuing 11 days. Affected by an easterly airstream, local weather turned mainly cloudy with a few light rain patches on October 25 and 26. As the band of clouds covering the coast of Guangdong thinned out, the weather remained generally fine on October 27 to 30. A cold front moved across the coastal areas of Guangdong in the morning of October 31 and brought cloudier weather with a few rain patches to the territory.
Four tropical cyclones occurred over the South China Sea and the western North Pacific in the month.
Details of issuance and cancellation of various warnings/signals in the month are summarised in Table 1. Monthly meteorological figures and departures from normal for October are tabulated in Table 2.
Ends/Tuesday, November 3, 2015
Issued at HKT 16:48
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