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The weather of August 2014 was hotter than usual due to prolonged spells of fine and sunny weather during the month. The monthly mean temperature of 29.0 degrees was 0.4 degrees higher than the normal figure of 28.6 degrees, while the monthly duration of bright sunshine of 212.0 hours was about 12 per cent above the normal figure of 188.9 hours. With two heavy rain episodes around mid-August, the month was also wetter than usual with a monthly rainfall amount of 548.2 millimetres, about 27 per cent above the normal August figure of 432.2 millimetres. The accumulated rainfall since January 1 was 2 312.1 millimetres, about 21 per cent above the normal figure of 1 905.5 millimetres for the same period.
The very hot weather at the end of July continued into the first day of August, with temperatures at the Hong Kong Observatory reaching a maximum of 34.6 degrees, the highest of the month. A southwesterly airstream maintained generally hot weather with sunny periods and a few thundery showers in the next three days. Under the influence of a trough of low pressure along the south China coast, local weather became cloudier and more showery with a few thunderstorms from August 5 to 7. With the weakening of the trough, the weather in Hong Kong turned generally fine on August 8 and 9.
Sunny periods and a few showers on August 10 and 11 were followed by outbreaks of heavy rain and thunderstorms on August 12 and 13 under the influence of an enhanced southwest monsoon associated with a trough of low pressure over the south China coastal areas. Around 270 millimetres of rainfall were recorded at the Observatory over these two days. A waterspout was observed over the waters south of Ap Lei Chau in the evening on August 12. As the trough weakened and the southwest monsoon moderated, rain eased off with sunny intervals on August 14.
Local weather remained generally fine on August 15 to 18 before unsettled weather with squally thunderstorms returned on August 19 and 20 as another trough of low pressure approached from southern China. Heavy rain over these two days brought over 130 millimetres of rainfall to the Observatory, and together with the downpour a week earlier, rainfall over the two heavy rain episodes amounted to 400 millimetres, more than 90 per cent of the normal level for August.
The weather stayed generally fine from August 21 to 30 apart from a cloudy and showery interlude on August 27 and 28 as an area of low pressure moved across the South China Sea. During its passage, easterly winds freshened along the coast of Guangdong and brought some relief from the sunny and very hot weather that prevailed during the period, with daytime temperatures at the Observatory exceeding 33 degrees on August 24 to 26 and again on August 29 and 30. Affected by showery activities associated with a broad trough of low pressure over the South China Sea, the weather turned mainly cloudy with a few showers and isolated thunderstorms on the last day of the month.
Three 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 August are tabulated in Table 2.
Ends/Tuesday, September 2, 2014
Issued at HKT 17:33
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