ENG-1994 — Page 491

THE ENVIRONMENT

days out of seven, with a monthly average at the Royal Observatory of 391.4 millimetres. The driest month is January, when the monthly average is only 23.4 millimetres and rain falls on only about six days in the month.

Severe weather phenomena that can affect Hong Kong include tropical cyclones, strong winter and summer monsoon winds, monsoon troughs and thunderstorms with associated squalls that are most frequent from April to September. Waterspouts and hailstorms occur infrequently, while snow and tornadoes are rare.

Climatological data are given in Appendix 50.

The Year's Weather

The year 1994 was very warm. The annual mean minimum temperature of 21.7°C and annual mean temperature of 23.6°C were the highest and the second highest, respectively, since records began in 1884. The year was also humid on the whole, with a mean dew-point temperature of 19.6°C, the highest on record. The first half of the year was particularly dry, with total rainfall amounting to only 556.9 millimetres 44 per cent below normal. However, record-breaking rainfall in July contributed to an overall annual total of 2 725.6 millimetres, 23 per cent above the annual mean of 2 214.3 millimetres. Only four tropical cyclones necessitated the hoisting of local tropical cyclone warning signals, compared with the annual average figure of about six.

With relatively few outbreaks of cold continental air towards the South China coastal areas, January was unusually warm and humid in Hong Kong. Despite the high humidity, only traces of rainfall were recorded at the Royal Observatory. This made January 1994 one of the six second-driest months of January on record.

February continued mild with high humidity. The monthly mean minimum temperature of 15.7°C and monthly mean dew-point temperature of 14.4°C were the seventh and the sixth highest, respectively, for February. The first thunderstorm of the year occurred during the month.

Frequent late-season monsoon surges made March cooler and cloudier than normal. The monthly mean pressure of 1 018.5 hectopascals was the fifth highest on record. On the other hand, it was relatively dry, both in terms of humidity and precipitation.

With a monthly rainfall of only 6.0 millimetres, April 1994 was the driest April since records began in 1884. It was also the warmest April on record. The mean air temperature of 24.7°C, the mean daily maximum temperature of 27.5°C and the mean daily minimum temperature of 22.8°C were all the highest for April.

May, on the whole, was hot and dry. With more sunshine than normal, the monthly mean temperature of 27.4°C ranked the fourth highest for May. Monsoon troughs affected the territory occasionally, bringing 183.7 millimetres of rainfall, about 58 per cent of the monthly normal.

Under the influence of warm southwest monsoons, June was cloudier and warmer than normal. There were 107.8 hours of bright sunshine, which was the seventh lowest figure on record. Severe Tropical Storm Russ became the first tropical cyclone in the year which necessitated the hoisting of local warning signals.

It was unsettled and extremely wet in July. The total rainfall of 1 147.2 millimetres was the highest for the month of July and the second highest for any month on record. During the heavy rain episode from July 22 to 24, a total of 611.2 millimetres was recorded at the

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