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The Weather of January 2006

     January 2006 was marked by hazy weather. The number of hours of reduced visibility observed at the Hong Kong International Airport reached 305 hours (i.e. about 41 % of the time) in the month. January 2006 was warmer than normal. The mean temperature of 16.4 degrees was 0.6 degrees above normal. The monthly rainfall of 16.3 millimetres was 7.1 millimetres less than normal.

     It was mainly fine and hazy on the first four days of January. A cold front moved across the south China coast on the early morning of 5 January. Under the influence of the northeast monsoon, the weather turned cold and dry on the following four days. The minimum temperature dropped to 8.0 degrees on 7 January, the lowest in the month.

     The temperature rose gradually on 10 and 11 January as the northeast monsoon weakened. It was fine and mild in the next five days.

     When a maritime airstream set in on 17 January, the weather became humid with morning mist. Misty conditions continued in the ensuing two days, and the visibility in the harbour once fell below 2000 metres on 19 January.

     Another cold front reached the south China coast on 20 January, bringing some rain to the territory for two days. It was cold and generally cloudy from 21 to 24 January. The weather turned milder on 25 and 26 January as clouds dispersed to give some sunny periods.

     A cloud band over the northern part of the South China Sea gradually extended to cover the South China coastal areas on 27 January. It was overcast and cool with occasional rain on 28 January. Clouds thinned out gradually during the day on 29 January. The weather became generally fine and mild for the last two days of the month. The maximum temperature rose to 23.6 degrees on the afternoon of 31 January, the highest in 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 1.2.  Monthly meteorological figures and departures from normal for January are tabulated in Table 2.


 

Warnings and Signals issued in January 2006


Table 1.1   Fire Danger Warnings

Colour Beginning Time Ending Time
Day/Month HKT Day/Month HKT
Yellow 1 / 1 0600 2 / 1 1800
Yellow 6 / 1 0600 7 / 1 0600
Red 7 / 1 0600 10 / 1 0600
Yellow 15 / 1 1130 15 / 1 1800
Yellow 22 / 1 0600 22 / 1 1800
Yellow 24 / 1 0600 27 / 1 1800
Yellow 30 / 1 1215 1 / 2 0600


Table 1.2   Cold Weather Warning

Beginning Time Ending Time
Day/Month HKT Day/Month HKT
5 / 1 1620 9 / 1 1645
20 / 1 1620 24 / 1 2315


Table 2   Figures and Departures from Normal - January 2006

Meteorological Element Figure of the Month Departure from Normal*
Mean Daily Maximum Air Temperature 18.4 degrees C 0.2 degree below normal
Mean Air Temperature 16.4 degrees C 0.6 degree above normal
Mean Daily Minimum Air Temperature 14.7 degrees C 1.1 degrees above normal
Mean Dew Point Temperature 12.7 degrees C 2.5 degrees above normal
Mean Relative Humidity 79 % 8 % above normal
Mean Cloud Amount 72 % 14 % above normal
Total Rainfall 16.3 mm 7.1 mm below normal
Number of hours of Reduced VisibilityΔ 305 hours 94.2 hours above normal§
Total Bright Sunshine Duration 123.1 hours 29.3 hours below normal
Mean Daily Global Solar Radiation 10.06 Megajoule / square metre 1.57 Megajoule below normal
Total Evaporation 65.8 mm 31.7 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 2005.


daily values of selected meteorological elements for HK for January 2006

Extract of Meteorological Observations in Hong Kong for January 2006