The Year's Weather - 2004
Globally, the year 2004 was the fourth warmest year since instrumental temperature record began in 1861. In Hong Kong, 2004 was the ninth warmest year on record. The annual mean temperature was 23.4 degrees, 0.4 degree above normal. In June 2004, the rain-bearing monsoon trough spent less time near the South China coast, resulting in more sunshine and hence higher temperatures in Hong Kong. This made June 2004 the eighth hottest June on record. The northeast monsoon was also weak during the last two months of the year, giving rise to above-normal temperatures in Hong Kong in these two months.
Three tropical cyclones affected Hong Kong this year, about half of the normal figure. Most of the tropical cyclones originating from the western North Pacific moved north or northeast on approaching Luzon and Taiwan and did not enter the South China Sea. They therefore failed to bring the usual rainfall to Hong Kong. The monsoon trough also brought less than normal rainfall to Hong Kong in May and June. Thus, 2004 turned out to be the seventeenth driest year in Hong Kong since records began in 1884. The annual rainfall of 1 738.6 millimetres was 475.7 millimetres or about 21 percent below normal. Similar dry condition was also widespread in southern China.
January was cloudier and wetter than usual. The monthly rainfall was 51.0 millimetres, more than double the normal figure.
February was warmer and slightly wetter than usual.
The deluge from a rainstorm late in the month made March wetter than usual. The monthly rainfall was 104.3 millimetres, about 56 per cent more than the normal figure.
In contrast to the first three months, April was slightly drier than usual.
Although May was drier than usual, the heavy downpour on 8 May led to the issuance of a Black Rainstorm Warning - the first such warning since September 2001. There were also reports of a tornado in the eastern part of Hong Kong during the rainstorm.
The weather of June was warmer, sunnier and drier than usual. The mean temperature of 28.6 degrees was 0.8 degree above normal, the eighth highest for June. The Standby Signal No. 1 was issued for the first time in the year to warn the public of Typhoon Conson in the South China Sea.
July was wetter than normal. Tropical Storm Kompasu made a direct hit on Hong Kong, necessitating the issuance of the No. 8 Gale or Storm Warning Signal.
Wetter-than-normal conditions continued in August. The Standby Signal No. 1 was issued during the approach of Typhoon Aere.
As none of the four tropical cyclones originating from the western Pacific came close to Hong Kong during the month, September was drier than usual. The monthly rainfall of 167.3 millimetres was about 44 percent below the normal figure.
October was sunnier and much drier than normal. The monthly rainfall of 2.3 mm amounted to only about 2 percent of the normal figure.
November and December were much warmer than usual, except for a cold snap in the last few days of the year. Both months were also very dry. November got 0.4 millimetre of rainfall, about 1 percent of normal, and December got just a trace of rainfall.
 Month |
Mean Pressure (hPa) |
Air Temperature | Mean Dew Point Temperature (deg. C) |
Mean Relative Humidity (%) |
Mean Amount of Cloud (%) |
Total Rainfall (mm) | ||
|---|---|---|---|---|---|---|---|---|
Mean Daily Maximum (deg. C) |
Mean (deg. C) |
Mean Daily Minimum (deg. C) | ||||||
| January | 1020.4 | 17.5 | 15.8 | 14.2 | 10.9 | 73 | 67 | 51.0 |
| February | 1018.4 | 19.4 | 17.2 | 15.4 | 13.3 | 79 | 62 | 51.8 |
| March | 1015.8 | 21.1 | 19.1 | 17.7 | 15.5 | 80 | 76 | 104.3 |
| April | 1012.6 | 25.3 | 22.9 | 21.2 | 19.8 | 83 | 76 | 147.2 |
| May | 1008.8 | 28.6 | 26.3 | 24.5 | 22.9 | 82 | 71 | 194.4 |
| June | 1006.8 | 30.8 | 28.6 | 26.8 | 24.3 | 78 | 66 | 144.7 |
| July | 1006.7 | 30.5 | 28.4 | 26.6 | 24.9 | 82 | 76 | 386.7 |
| August | 1003.5 | 30.7 | 28.4 | 26.5 | 24.8 | 82 | 64 | 488.5 |
| September | 1009.9 | 29.9 | 27.6 | 25.9 | 23.1 | 77 | 62 | 167.3 |
| October | 1016.1 | 27.5 | 24.9 | 22.9 | 17.5 | 64 | 35 | 2.3 |
| November | 1018.6 | 24.5 | 22.7 | 21.1 | 17.5 | 73 | 50 | 0.4 |
| December | 1019.3 | 21.1 | 19.1 | 17.2 | 13.1 | 70 | 40 | Trace |
| Mean/Total | 1013.1 | 25.6 | 23.4 | 21.7 | 19.0 | 77 | 62 | 1738.6 |
| Normal | 1012.9 | 25.7 | 23.0 | 20.9 | 18.6 | 77 | 65 | 2214.3 |
| Station | Hong Kong Observatory | |||||||
Month |
Total Bright Sunshine (hours) |
Mean Daily Global Solar Radiation (MJ/m2) |
Total Evaporation (mm) |
Prevailing Wind Direction (degrees) |
Mean Wind Speed (km/h) |
|---|---|---|---|---|---|
| January | 136.8 | 9.88 | 70.3 | 050 | 26.7 |
| February | 140.7 | 11.22 | 64.6 | 050 | 21.4 |
| March | 95.5 | 9.46 | 68.7 | 070 | 22.7 |
| April | 115.8 | 12.90 | 97.5 | 090 | 17.5 |
| May | 163.5 | 15.50 | 122.5 | 090 | 15.1 |
| June | 205.3 | 17.32 | 152.6 | 100 | 20.1 |
| July | 172.2 | 14.71 | 132.1 | 230 | 23.1 |
| August | 165.9 | 13.69 | 129.2 | 240 | 16.1 |
| September | 190.5 | 15.09 | 134.1 | 090 | 14.4 |
| October | 257.4 | 16.36 | 145.0 | 090 | 22.9 |
| November | 183.9 | 12.13 | 98.4 | 080 | 24.1 |
| December | 216.6 | 12.32 | 99.4 | 080 | 26.8 |
| Mean/Total | 2044.1 | 13.38 | 1314.4 | 080 | 20.9 |
| Normal | 1948.1 | 14.46 | 1528.8 | 080 | 22.6 |
| Station | King's Park | Waglan Island^ | |||
The minimum pressure recorded at the Hong Kong Observatory was 992.4 hectopascals at 0234 HKT on 27 August. The maximum air temperature recorded at the Hong Kong Observatory was 34.6 degrees Celsius at 1607 HKT on 1 July. The minimum air temperature recorded at the Hong Kong Observatory was 7.7 degrees Celsius at 0714 HKT on 9 February. The maximum gust peak speed recorded at Waglan Island was 106 kilometres per hour from 220 degrees at 1617 HKT on 16 July. The maximum instantaneous rate of rainfall recorded at King's Park was 156 millimetres per hour at 1218 HKT on 21 August. Trace - rainfall amount less than 0.05 mm ^ In case the data are not available from Waglan Island, observations of Cheung Chau or other nearby weather stations will be incorporated in computing the Prevailing Wind Direction and Mean Wind Speed |