Hong Kong's climate is subtropical, tending towards the temperate for nearly half the year. November and December are generally regarded as the best months of the year with pleasant breezes, plenty of sunshine and comfortable temperatures.

January and February are cloudier, with occasional cold fronts bringing in cold northerly winds. Temperatures can drop below 10 degrees Celsius in urban areas. Sub-zero temperatures and frost occur infrequently on high ground.

March and April can be mild and pleasant but humid. Fog sometimes disrupts air traffic and ferry services because of reduced visibility.

The months from May to August are hot and humid with occasional showers and thunderstorms. Afternoon temperatures often exceed 31 degrees, but at night temperatures generally stay around 26 degrees.

Hong Kong is more likely to be affected by tropical cyclones between June and October. When a tropical cyclone is some 1 000 kilometres southeast of Hong Kong, the weather is usually fine and exceptionally hot. If the centre of the tropical cyclone comes closer to Hong Kong, winds will increase and rain may become heavy and widespread. Landslips and flooding sometimes cause considerably more damage than the winds.

About 80 per cent of the annual rainfall falls between May and September. August is the wettest month and January the driest.

Severe weather phenomena in Hong Kong include tropical cyclones, strong winter and summer monsoon winds, monsoon troughs and thunderstorms with associated squalls. Waterspouts and hailstorms occur infrequently, while snow and tornadoes are rare.

The Year's Weather

Globally, 2004 was the fourth warmest year since instrumental temperature records 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, 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 in 2004, 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 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 percent 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 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, 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.

The weather in 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 per cent below the normal figure.

October was sunnier and much drier than normal. The monthly rainfall of 2.3 millimetres amounted to only about 2 per cent 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. There was 0.4 millimetre of rainfall in November, about 1 per cent of normal, and just a trace of rainfall in December.