The Weather of January 2009
January 2009 was sunnier and drier than usual. The total bright sunshine duration for the month was 226.5 hours, about 60 percent above the normal figure of 141.7 hours. Only a trace of rainfall was recorded during the month, making it the driest January since 1994. The monthly mean temperature of 15.3 degrees was 0.8 degrees below normal.
Under the influence of a strong winter monsoon, the weather was fine, dry and cold in the first three days of the year. The temperature rose a couple of degrees on 4 January as the winter monsoon weakened. The weather remained cool, fine and dry for the ensuing three days.
A replenishment of the northeast monsoon brought cold and very dry conditions to the territory on 8 January. It stayed cold in the next eight days. The temperature recorded at Ta Kwu Ling fell to a minimum of -0.8 degrees on the morning of 11 January, the lowest since record began in 1985. Frost was reported at Ta Kwu Ling and Shatin on 11 January and Kau Sai Chau on 12 January.
The weather stayed fine and dry from 17 to 19 January. Under the influence of a fresh to strong easterly airstream, the weather became mainly cloudy on 20 January. It turned sunny and warm the next day when the easterlies moderated. Under light wind conditions, it was hazy on 22 January.
The cold air associated with an intense winter monsoon reached the south China coastal areas in the evening of 23 January bringing cloudy and rather cool weather to Hong Kong. It was generally cloudy and cold in the ensuing four days. With the moderation of the northeast monsoon, temperatures rose gradually during the next two days. It was generally fine for the last two days of the month.
There was no tropical cyclone over the South China Sea and the western North Pacific in the month.