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December 2007 was warm and hazy and the mean temperature of 19.3 degrees was 1.7 degrees above normal. It was the fourth highest for December. The number of hours of reduced visibility observed at the Hong Kong Observatory was 305 hours (41 % of the time) in December. Total rainfall for the month was 15.7 millimetres, about 58% of the normal figure of 27.3 millimetres. The accumulated rainfall since the beginning of the year was 1706.9 millimetres, about 23% below the normal figure of 2214.3 millimetres for the same period.
A ridge of high pressure over southern China brought generally fine weather to Hong Kong on the first two days of the month. Local winds strengthened from the north on December 3 after a cold front moved across the south China coast. Under the influence of a continental airstream, it was mainly fine and dry on December 4.
The weather became cloudy on December 5 as a cloud band covered the coast of Guangdong. Clouds thinned out quickly the next day and there were sunny periods. With the northeast monsoon prevailing over southern China, it was mainly fine but hazy between December 7 and 9.
The northeast monsoon moderated on December 10 and the weather was sunny and warm in the next two days. Haze returned on December 13 with visibility at the Hong Kong International Airport dropping to below 2000 metres. The weather remained generally fine but hazy in the ensuing two days.
The weather turned cloudy on December 16 when a broad cloud band affected the coast of Guangdong. It was cloudy with a few light rain patches in the following six days.
A replenishment of the northeast monsoon reached the south China coast on December 23, bringing cooler weather in the ensuing three days. Generally fine weather persisted from December 26-28.
The temperature dropped progressively on December 29 and 30 upon the arrival of the cold air associated with an intense winter monsoon. The weather was cold and very dry on December 31 with temperatures falling to 12 degrees, the lowest of the month.
There was no tropical cyclone 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 1.1. Monthly meteorological figures and departures from normal of December are tabulated in Table 1.2.
Ends/Thursday, January 3, 2008
Issued at HKT 15:58
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