The Weather of February 2005

Characterized by the foggy and cloudy weather resulting from the tug-of-war between the northeast monsoon and the maritime airstream around the south China coast, February 2005 was gloomier and more humid than usual. The monthly mean relative humidity of 86 percent was 8 percent higher than normal and ranked the fourth highest for February. The total duration of bright sunshine was only 34.4 hours, about one third of the normal figure. In spite of the humid weather, the monthly rainfall of 19.2 millimetres was 28.8 millimetres less than normal.

Under the influence of the winter monsoon, it was cold and overcast with rain patches in the first three days of February. On 4 February, the temperature started to rise gradually when a maritime airstream set in. The maritime airstream also brought foggy weather to the Hong Kong waters for 5 days in a role. While the visibility improved slightly on 9 February, it remained misty and humid with light rain patches.

A cold front moved across the south China coast during the day on 10 February. It became cooler the next day. Although there were sunny periods on 12 February, it turned cloudy again on 13 and 14 February.

A maritime airstream brought humid and foggy weather to Hong Kong again in the next three days. On 17 February, a mainland catamaran collided with a cargo ship over the sea area off Tsing Yi under heavy fog that morning. Over 100 people were injured in the accident. Later in the day, a cold front arrived at the coast of Guangdong, bringing cold and overcast weather to Hong Kong in the following five days. The temperatures in the urban area dropped to 9 degrees on 20 February, the lowest of the month. On 23 February, fog returned when Hong Kong once again came under the influence of a maritime airstream. It remained foggy in the following two days. At the height of the foggy episode on the morning of 25 February, the visibility at the Hong Kong International Airport once fell to about 200 metres. 46 flights were delayed or diverted. 17 scheduled ferry trips between Hong Kong and Guangdong were also cancelled. The arrival of an intense northeast monsoon later during the day on 25 February eventually cleared the fog. It was windy, rainy and appreciably cooler in the following two days.

It was cold and rainy on the last day of February.

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 February are tabulated in Table 2.

Warnings and Signals issued in February 2005

Table 1.1 Strong Monsoon Signal

Beginning Time		Ending Time
Day/Month	HKT	Day/Month	HKT
13 / 2	2315	14 / 2	1200
25 / 2	1930	27 / 2	1530

Table 1.2 Thunderstorm Warning

Beginning Time		Ending Time
Day/Month	HKT	Day/Month	HKT
27 / 2	0955	27 / 2	1055

Table 1.3 Fire Danger Warnings

Colour	Beginning Time		Ending Time
Colour	Day/Month	HKT	Day/Month	HKT
Yellow	11 / 2	0600	11 / 2	1800
Yellow	19 / 2	0600	21 / 2	0600

Table 1.4 Cold Weather Warning

Beginning Time		Ending Time
Day/Month	HKT	Day/Month	HKT
30 / 1	2325	3 / 2	1615
18 / 2	0800	23 / 2	0600
26 / 2	2325	1 / 3	1145

Table 2 Figures and Departures from Normal - February 2005

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	16.5 degrees C	0.6 degree above normal
Mean Daily Minimum Air Temperature	14.8 degrees C	0.9 degree above normal
Mean Dew Point Temperature	14.0 degrees C	2.2 degrees above normal
Mean Relative Humidity	86 %	8 % above normal
Mean Cloud Amount	91 %	18 % above normal
Total Rainfall	19.2 mm	28.8 mm below normal
Number of hours of Reduced VisibilityΔ	131 hours	26.6 hours above normal§
Total Bright Sunshine Duration	34.4 hours	63.3 hours below normal
Mean Daily Global Solar Radiation	6.02 Megajoule / square metre	4.67 Megajoule below normal
Total Evaporation	35.1 mm	43.9 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.
* 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 February 2005

Extract of Meteorological Observations in Hong Kong for February 2005