The Weather of August 2003

August 2003 was cloudier and wetter than usual. The monthly mean cloud amount of 71 per cent was 5 per cent higher than the normal figure. The monthly rainfall of 415.0 millimetres was 6 per cent above the normal figure of 391.4 millimetres. However, the accumulated rainfall since the beginning of the year was 1 449.2 millimetres, about 15 per cent below the normal figure of 1 707.4 millimetres for the same period. 

It was mainly fine in the first 3 days of August. With plenty of sunshine, temperature rose to 33.7 degrees on 3 August, the highest of the month. Tropical Storm Morakot brought some heavy thundery showers to Hong Kong in the evening of 4 August after it traversed the Taiwan Strait and made landfall near Xiamen. It remained cloudy with showers on 5 and 6 August.

The weather became mainly fine on 7 August and remained so for 9 days. Under the influence of a weak southwest monsoon, there were also a few showers which became more frequent on 11 August as a broad area of low pressure developed over southern China. A trough of low pressure moved south across the south China coast and brought heavy showers and thunderstorms to the territory on 17 August. The weather turned fine the following day.

Tropical Depression Vamco developed over the Pacific to the northeast of Luzon on 19 August. As it moved northwestward, an area of low pressure near Dongsha drifted towards the south China coast. Occasional showers developed in Hong Kong which became heavy on 21 and 22 August. The weather turned fine briefly on 23 August. 

On the morning of 23 August, Typhoon Krovanh which developed over the western North Pacific moved west across Luzon into the South China Sea, necessitating the issuance of the No. 1 Standby Signal. The No. 3 Strong Wind Signal was issued on 24 August as the typhoon moved across the northern part of the South China Sea in the direction of Leizhou Peninsula. Krovanh came closest to Hong Kong at about 340 kilometres to the southwest that evening. The outer rainbands of Krovanh brought heavy showers to Hong Kong on 24 and 25 August. The weather improved after Krovanh made landfall over the coast of northernVietnam during the small hours of 26 August.

It remained fine and hot from 27 to 31 August. On the last day of the month, intense heat during the day triggered the development of thunderstorms inland to the northeast of Hong Kong. The thunderstorms drifted south and affected Hong Kong just before midnight. 

A total of 5 tropical cyclones occurred in the western North Pacific and the South China Sea in the month. 

Details of issuance and cancellation of various warnings/signals in the month are summarized in Tables 1.1 to 1.4.  Monthly meteorological figures and departures from normal for August are tabulated in Table 2.