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With the dominance of a dry northeast monsoon for most of the month, October 2013 was sunnier and drier than usual. The monthly total duration of bright sunshine was 247.3 hours, about 28 per cent above the normal figure of 193.9 hours. The monthly mean relative humidity of 66 per cent was the third lowest for October since 1961. Also, the monthly total rainfall was 2.9 millimetres, only about three per cent of the normal figure of 100.9 millimetres. However, the accumulated rainfall since January 1 of 2,675.9 millimetres was still about 15 per cent above the normal figure of 2,334.0 millimetres for the same period. October 2013 was also slightly warmer than usual. The monthly mean temperature of 25.7 degrees was 0.2 degrees above the normal figure of 25.5 degrees.
Under the influence of a dry northeast monsoon, the weather in Hong Kong was fine and dry for the first seven days of the month. With abundant sunshine, temperatures at the Hong Kong Observatory rose to a maximum of 32.0 degrees on October 7, the highest of the month. As a cloud band moved over southern China, the weather in Hong Kong turned cloudy with a few rain patches on October 8. Clouds dissipated gradually on October 9 and, apart from some nocturnal rain, the weather was mainly fine in the next three days.
Meanwhile, Typhoon Nari moved across Luzon and entered the South China Sea on October 12. Nari tracked generally westwards over the next two days and made landfall in central Vietnam on the morning of October 15. Under the combined effect of Nari and a fresh to strong northeast monsoon over the coast of Guangdong, it was windy in Hong Kong on October 13 and 14. The outer rainbands of Nari also brought mainly cloudy weather and a few rain patches on October 14 and the next morning.
A cold front from inland Guangdong edged southwards on October 15 and moved across the coastal areas the next morning. Affected by the cold front, the weather in Hong Kong became cloudy and windy with light rain patches on October 16 and 17. With clouds thinning out, local weather became fine and dry on October 18. Dominated by a dry continental airstream, daytime relative humidity fell to 40 per cent or below from October 23 to 26. Meanwhile, a replenishment of the northeast monsoon reached the south China coast on the morning of October 26, bringing cooler weather to Hong Kong. Temperatures at the Hong Kong Observatory fell to a minimum of 19.4 degrees that morning, the lowest of the month. Under the influence of the northeast monsoon, the weather remained generally fine till the end of the month.
Eight tropical cyclones occurred over the South China Sea and the western North Pacific in the month.
Details of the 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/Monday, November 4, 2013
Issued at HKT 19:34
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