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The Weather of October 2005

    October 2005 was warmer and drier than normal. The monthly mean temperature of 26.2 degrees was 1.0 degree higher than the normal and ranked the third highest for October. The total rainfall of 6.6 millimetres was only about 5 percent of the normal figure. The accumulated rainfall since the beginning of the year is 3203.4 millimetres, about 49 percent above the normal figure of 2151.9 millimetres for the same period.

    Apart from a few isolated showers, it was fine, hot and hazy on the first three days of the month. Under the influence of the hot subsiding air ahead of Typhoon Longwang, the maximum temperature rose to 32.4 degrees on 2 October, the highest in the month. Visibility improved on 4 October when winds freshened from the north. With the northeast monsoon prevailing over southern China, the weather stayed generally fine for the next ten days. There were over 50 reports of hill fire during the Chung Yeung Festival on 11 October.

    Haze returned on 15 October when local winds abated. Visibility in the harbour dropped below 5000 metres. The hazy condition persisted in the ensuing two days. Winds strengthened from the east on 18 October, which cleared the haze and brought fine weather to the territory on 19 and 20 October. A replenishment of the northeast monsoon arrived at the south China coast on 21 October, bringing dry and slightly cooler to the territory in the following three days. The Red Fire Danger Warning was in force between 22 and 24 October. The weather remained sunny until 28 October.

    A surge of northeast monsoon brought cloudy and cooler weather to the territory on 29 and 30 October. The minimum temperature dropped further to 20.5 degrees in the morning of 31 October, the lowest in the month.

    Four tropical cyclones occurred in the western North Pacific and South China Sea 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 October are tabulated in Table 2.


 

Warnings and Signals issued in October 2005


Table 1.1   Strong Monsoon Signal

Beginning Time Ending Time
Day/Month HKT Day/Month HKT
18 / 10 2200 19 / 10 0745


Table 1.2   Thunderstorm Warning

Beginning Time Ending Time
Day/Month HKT Day/Month HKT
2 / 10 0420 2 / 10 0600
2 / 10 1525 2 / 10 1915
4 / 10 2250 5 / 10 0030


Table 1.3   Fire Danger Warnings

Colour Beginning Time Ending Time
Day/Month HKT Day/Month HKT
Yellow 1 / 10 0000 2 / 10 0420
Yellow 2 / 10 1100 2 / 10 1700
Yellow 8 / 10 0600 9 / 10 2200
Yellow 11 / 10 0000 11 / 10 2400
Yellow 15 / 10 0600 16 / 10 2315
Yellow 22 / 10 0000 22 / 10 0630
Red 22 / 10 0630 24 / 10 1800
Yellow 29 / 10 0600 31 / 10 0600


Table 2   Figures and Departures from Normal - October 2005

Meteorological Element Figure of the Month Departure from Normal*
Mean Daily Maximum Air Temperature 28.3 degrees C 0.4 degree above normal
Mean Air Temperature 26.2 degrees C 1.0 degree above normal
Mean Daily Minimum Air Temperature 24.4 degrees C 1.3 degrees above normal
Mean Dew Point Temperature 20.6 degrees C 0.8 degree above normal
Mean Relative Humidity 72 % 1 % below normal
Mean Cloud Amount 57 % 1 % above normal
Total Rainfall 6.6 mm 138.2 mm below normal
Number of hours of Reduced VisibilityΔ 205 hours 101.2 hours above normal§
Total Bright Sunshine Duration 221.7 hours 26.7 hours above normal
Mean Daily Global Solar Radiation 14.63 Megajoule / square metre 0.83 Megajoule below normal
Total Evaporation 135.0 mm 17.2 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 1961-1990 climatological normal, except for number of hours of reduced visibility.
  §   Departure from mean value between 1997 and 2004.


daily values of selected meteorological elements for HK for October 2005

Extract of Meteorological Observations in Hong Kong for October 2005