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The Weather of January 2008

    January 2008 was cloudier and wetter than usual. The total bright sunshine duration of 124.8 hours was 16.9 hours below normal. The total rainfall in the month was 33.3 millimetres, about 34 percent above normal. Although the monthly mean temperature of 15.9 degrees was similar to the normal figure of 16.1 degrees, the mean minimum temperature of 10.8 degrees during the cold spell from 24 to 31 January was the eighth lowest for the same period since 1947. The Cold Weather Warning was issued for a consecutive of 177 hours till the end of the month.

    Under the influence of a strong winter monsoon, the weather was fine, dry and cold in the first three days. Frost was reported at Kau Sai Chau on the morning of 2 January. The weather remained fine and dry with temperatures rising gradually on 4 January. Hazy conditions set in on 5 January and persisted in the ensuing four days.

    The weather became foggy from 10 to 12 January when Hong Kong came under the influence of a warm and humid easterly airstream. Temperatures fell during the day on 13 January after the passage of a cold front across the south China coast. The northeast monsoon behind the cold front brought generally cloudy and cold weather to the territory in the next four days. Temperatures rose slightly during the day on 18 January when the northeast monsoon was replaced by a fresh to strong easterly airstream. The weather stayed mild with sunny intervals in the next two days.

    Another cold front reached the south China coast on the morning of 21 January. The northeast monsoon behind the cold front brought cool and dry weather to the territory on that day. With the northeast monsoon dominating over southern China, the weather stayed mainly cloudy and cool with sunny intervals on 22 and 23 January. Under the combined effect of the northeast monsoon and a broad rain band, cold and rainy weather prevailed in the ensuing eight days. The minimum temperature dropped to 8.5 degrees on 31 January, the lowest so far this winter. Frost was reported at Kau Sai Chau in that morning.

    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 1.4.  Monthly meteorological figures and departures from normal for January are tabulated in Table 2.


 

Warnings and Signals issued in January 2008


Table 1.1   Strong Monsoon Signal

Beginning Time Ending Time
Day/Month HKT Day/Month HKT
18 / 1 2245 19 / 1 0545


Table 1.2   Fire Danger Warnings

Colour Beginning Time Ending Time
Day/Month HKT Day/Month HKT
Red 30 / 12 0600 4 / 1 0600
Yellow 4 / 1 0600 5 / 1 1100
Red 5 / 1 1100 6 / 1 0600
Yellow 6 / 1 0600 7 / 1 0600
Yellow 7 / 1 1130 8 / 1 0600
Yellow 14 / 1 0600 14 / 1 1800
Yellow 16 / 1 1145 17 / 1 0345
Yellow 20 / 1 1230 21 / 1 0600
Yellow 21 / 1 1145 21 / 1 2315
Yellow 23 / 1 0600 24 / 1 0600


Table 1.3   Frost Warning

Beginning Time Ending Time
Day/Month HKT Day/Month HKT
31 / 12 1620 1 / 1 0745
1 / 1 1630 2 / 1 0945
2 / 1 2245 3 / 1 0845


Table 1.4   Cold Weather Warning

Beginning Time Ending Time
Day/Month HKT Day/Month HKT
30 / 12 1620 4 / 1 0945
13 / 1 1620 14 / 1 0950
15 / 1 1620 18 / 1 1020
24 / 1 1500 18 / 2 0930


Table 2   Figures and Departures from Normal - January 2008

Meteorological Element Figure of the Month Departure from Normal*
Mean Daily Maximum Air Temperature 18.3 degrees C 0.3 degree below normal
Mean Air Temperature 15.9 degrees C 0.2 degree below normal
Mean Daily Minimum Air Temperature 14.0 degrees C 0.1 degree below normal
Mean Dew Point Temperature 11.1 degrees C 0.1 degree above normal
Mean Relative Humidity 75 % 2 % above normal
Mean Cloud Amount 68 % 8 % above normal
Total Rainfall 33.3 mm 8.4 mm above normal
Number of hours of Reduced VisibilityΔ 226 hours 13.0 hours below normal§
Total Bright Sunshine Duration 124.8 hours 16.9 hours below normal
Mean Daily Global Solar Radiation 9.47 Megajoule / square metre 1.08 Megajoule below normal
Total Evaporation 66.4 mm 14.3 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.


  *   Departure from 1971 - 2000 climatological normal, except for number of hours of reduced visibility

  §   Departure from mean value between 1997 and 2007


daily values of selected meteorological elements for HK for January 2008

Extract of Meteorological Observations in Hong Kong for January 2008