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The Weather of January 2007

    January 2007 was warmer than usual. The mean temperature of 16.4 degrees was 0.6 degree above normal. The monthly rainfall was 29.6 millimetres, which was 6.2 millimetres above normal.

    The year 2007 started fine and mild. Cloudy conditions set in and there were some rain on 2 and 3 January. The weather stayed cloudy on 4 January and then turned fine and rather cool on 5 January when a surge of the northeast monsoon arrived at southern China. It was fine, dry and cold in the ensuing four days. The temperature fell to 10.9 degrees on 8 January, the lowest in the month. Frost was reported at Ta Kwu Ling on the morning of 8 and 9 January.

    The weather became cloudy on 10 January and remained so until 12 January. Under the influence of a dry northeast monsoon, it turned mainly fine and hazy on 13 and 14 January. With the weakening of the northeast monsoon, it was mild on 15 and 16 January. A replenishment of the northeast monsoon brought rainy and cooler weather to the territory on 17 January. The weather remained cool with a few rain patches in the next five days.

    The weather improved gradually with sunny periods from 23 to 25 January. The strengthening of the northerlies brought fine, dry and cold weather to Hong Kong on 26 January and the following three days. With abundant sunshine, the temperature recovered gradually on 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.

    Details of issuance and cancellation of various warnings/signals in the month are summarized in Tables 1.1 to 1.3.  Monthly meteorological figures and departures from normal for January are tabulated in Table 2.


 

Warnings and Signals issued in January 2007


Table 1.1   Fire Danger Warnings

Colour Beginning Time Ending Time
Day/Month HKT Day/Month HKT
Yellow 30 / 12 0645 1 / 1 1800
Yellow 5 / 1 0600 6 / 1 1130
Red 6 / 1 1130 10 / 1 1630
Yellow 13 / 1 0600 14 / 1 1800
Yellow 24 / 1 0600 26 / 1 1600
Red 26 / 1 1600 30 / 1 0600
Red 30 / 1 1330 3 / 2 0600


Table 1.2   Frost Warning

Beginning Time Ending Time
Day/Month HKT Day/Month HKT
7 / 1 2235 8 / 1 0830
8 / 1 1630 9 / 1 0900


Table 1.3   Cold Weather Warning

Beginning Time Ending Time
Day/Month HKT Day/Month HKT
5 / 1 1620 9 / 1 1045
26 / 1 1620 30 / 1 1045


Table 2   Figures and Departures from Normal - January 2007

Meteorological Element Figure of the Month Departure from Normal*
Mean Daily Maximum Air Temperature 18.8 degrees C 0.2 degree above normal
Mean Air Temperature 16.4 degrees C 0.6 degree above normal
Mean Daily Minimum Air Temperature 14.3 degrees C 0.7 degree above normal
Mean Dew Point Temperature 10.9 degrees C 0.7 degree above normal
Mean Relative Humidity 72 % 1 % above normal
Mean Cloud Amount 59 % 1 % above normal
Total Rainfall 29.6 mm 6.2 mm above normal
Number of hours of Reduced VisibilityΔ 427 hours 206.8 hours above normal§
Total Bright Sunshine Duration 157.9 hours 5.5 hours above normal
Mean Daily Global Solar Radiation 10.98 Megajoule / square metre 0.65 Megajoule below normal
Total Evaporation 73.6 mm 23.9 mm below normal


  Remarks : All measurements were made at the Hong Kong Observatory except sunshine, solar radiation and evaporation which were recorded at King's Park Meteorological Station and visibility which was observed at the Hong Kong International Airport.
  Δ

The visibility readings at the Hong Kong International Airport are based on hourly observations by professional meteorological observers in 2004 and before, and average readings over the 10-minute period before the clock hour of the visibility meter near the middle of the south runway from 2005 onwards. The change of the data source in 2005 is an improvement of the visibility assessment using instrumented observations following the international trend.

Before 10 October 2007, the number of hours of reduced visibility at the Hong Kong International Airport in 2005 and thereafter displayed in this web page was based on hourly visibility observations by professional meteorological observers. Since 10 October 2007, the data have been revised using the average visibility readings over the 10-minute period before the clock hour, as recorded by the visibility meter near the middle of the south runway.


 

The calibration factors of the pyranometer at King's Park in 2006 and 2007 have been re-computed based on the results of a regional instrument comparison in Asia in 2007. The readings of total global solar radiation at King's Park in 2006 and 2007 displayed in this web page before 13 June 2008 have been revised on 13 June 2008 using the new calibration factors.

  *   Departure from 1961-1990 climatological normal, except for number of hours of reduced visibility.
  §   Departure from mean value between 1997 and 2006.
daily values of selected meteorological elements for HK for January 2007

Extract of Meteorological Observations in Hong Kong for January 2007