Globally, 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 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. 2004 was the 17th 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% below normal. Similar dry conditions were 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% more than the normal figure.
In contrast to the first three months, April was slightly drier than usual.
Although May was drier than usual, a heavy downpour on May 8 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.
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 people 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% below the normal figure.
October was sunnier and much drier than normal. The monthly rainfall of 2.3 mm amounted to only about 2% 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% of normal, and December got just a trace of rainfall.