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In the northern hemisphere, 2007 was the second warmest year on record. In Hong Kong, 2007 was the fifth warmest year since records began in 1884. The annual mean temperature of 23.7 degrees was 0.7 degree higher than normal. With a weaker northeast monsoon, February's mean temperature of 19.5 degrees was the highest on record for that month. The year saw another new record of hot weather as the Very Hot Weather Warning was issued for 13 consecutive days during a hot spell in late July and early August. The year was also drier than usual. The annual rainfall of 1706.9 millimetres was about 23% below normal.
In 2007, a total of 25 tropical cyclones formed over the western North Pacific and the South China Sea, which was below normal. Only two tropical cyclones, Severe Tropical Storm Pabuk and Tropical Storm Francisco, affected Hong Kong, fewer than the normal number of six or seven. Among them, Pabuk necessitated the issuance of the first Number 8 Gale or Storm Signal since the passage of Tropical Storm Kompasu in 2004.
The less-than-normal rainfall and fewer tropical cyclones affecting Hong Kong were mainly due to the stronger-than-normal sub-tropical ridge of high pressure over the western North Pacific and the South China Sea in July, September and October, suppressing the convection over the areas.
The first quarter (January to March) in 2007 was much warmer than normal. The mean temperature of 18.7 degrees was the fifth highest on record.
It became cooler than usual in April. The mean temperature of 21.8 degrees was 0.4 degree below normal.
May was warmer and sunnier than usual. The total bright sunshine duration of 183.4 hours was about 19% above normal.
Under the influence of active troughs of low pressure and southerly airstream, June was wetter than usual. The monthly rainfall of 490.1 millimetres was about 30% above normal. Severe gusts with speed reaching 129 kilometres per hour were recorded at the Hong Kong International Airport on the morning of June 8 when squally thunderstorms affected the territory. A Government Flying Service helicopter parked on the apron toppled over in the gusty winds associated with the thunderstorms.
July was unseasonably dry and warm. The monthly rainfall of 76.9 millimetres, less than one fourth of the normal figure of 323.5 millimetres, was the lowest on record for July. The monthly mean temperature rose to 29.6 degrees, the second highest for July.
August was cloudier and wetter than usual with only 134.3 hours of bright sunshine, the second lowest for August. The No 8 Gale or Storm Signal was issued on the approach of Severe Tropical Storm Pabuk.
September and October were drier than normal.
November was cooler than usual. The mean temperature of 20.9 degrees was 0.5 degree below normal.
December was warm and hazy. The monthly mean temperature mounted to 19.3 degrees, the fourth highest for December.
Figures 1 and 2 showed respectively the comparison of the monthly mean temperature and monthly rainfall in 2007 with the climatological normal values.
Ends/Thursday, January 3, 2008
Issued at HKT 16:15
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