The Weather of February 2009

February 2009 was the warmest February since records began in 1884. The monthly mean temperature of 20.5 degrees was 4.2 degrees higher than normal. The temperature of 28.3 degrees recorded on February 25 was the highest temperature for February. The month was also sunnier than normal. The total bright sunshine duration for the month was 140.7 hours, about 50 percent above normal. Only 1.1 millimetres of rainfall was recorded in February 2009, much below the normal figure of 52.3 millimetres.

The weather in Hong Kong was generally cloudy on the first day of the month. Under the influence of a ridge of high pressure over southeastern China, the local weather became fine on 2 February. It remained generally fine for the ensuing 9 days.

A humid maritime airstream dominated over the south China coastal areas and brought cloudy and humid weather to the territory from 12 to 15 February. It was also foggy on 15 February. The visibility dropped below 400 meters in the harbour on that day.

Under the influence of an easterly airstream, the weather in Hong Kong was windy, rainy and slightly cooler from 16 to 18 February. It remained cloudy with light rain patches on 19 February.

A dry northerly airstream reached the south China coastal areas on the morning of 20 February. Locally, weather became fine later that day. With the winds turning to easterly, it was windy and cloudy on 21 February. Local winds subsided gradually the next day.

It was humid with fog from 23 to 25 February when Hong Kong was affected by a warm and humid maritime airstream. The temperature at the Hong Kong Observatory rose to a maximum of 28.3 degrees on 25 February, the highest of the month. A weak replenishment of the northeast monsoon reached the coastal areas of Guangdong on the morning of 26 February and brought cloudy and cooler weather to Hong Kong for the last three 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. Monthly meteorological figures and departures from normal for February are tabulated in Table 2.

Warnings and Signals issued in February 2009

Table 1.1 Fire Danger Warnings

Colour	Beginning Time		Ending Time
Colour	Day/Month	HKT	Day/Month	HKT
Yellow	1 / 2	0600	2 / 2	1800
Yellow	8 / 2	0600	9 / 2	0600

Table 2 Figures and Departures from Normal - February 2009

Meteorological Element	Figure of the Month	Departure from Normal*
Mean Daily Maximum Air Temperature	23.7 degrees C	5.1 degrees above normal
Mean Air Temperature	20.5 degrees C	4.2 degrees above normal
Mean Daily Minimum Air Temperature	18.6 degrees C	4.2 degrees above normal
Mean Dew Point Temperature	17.1 degrees C	4.9 degrees above normal
Mean Relative Humidity	81 %	3 % above normal
Mean Cloud Amount	64 %	9 % below normal
Total Rainfall	1.1 mm	51.2 mm below normal
Number of hours of Reduced VisibilityΔ	137 hours	8.7 hours below normal§
Total Bright Sunshine Duration	140.7 hours	46.9 hours above normal
Mean Daily Global Solar Radiation	12.70 Megajoule / square metre	3.09 Megajoule above normal
Total Evaporation	74.2 mm	6.6 mm above 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 2008

daily values of selected meteorological elements for HK for February 2009

Extract of Meteorological Observations in Hong Kong for February 2009