The Weather of July 2003

July 2003 was warmer and drier than usual. The monthly mean minimum temperature of 27.6 degrees equaled the record high value set in 1993. The monthly rainfall of 101.8 millimetres, less than one third of the normal figure of 323.5 millimetres, was the lowest on record. The accumulated rainfall since the beginning of the year was 1 034.2 millimetres, about 21 percent below the normal figure of 1 316.0 millimetres for the same period. 

With a strong ridge of high pressure dominating over southern China, sunny weather persisted in Hong Kong for the first 19 days. The Very Hot Weather Warning was in force for 14 days. The intense heat triggered the development of isolated but heavy showers. Waterspouts and funnel clouds were reported on 1, 6 and 9 July.

On 20 July, the first tropical cyclone warning in the year was issued. Severe Tropical Storm Koni skirted about 530 kilometers to the southwest of Hong Kong the next day, bringing occasional heavy showers and thunderstorms to Hong Kong in the evening.

The weather became fine and hot on 22 July as Typhoon Imbudo traversed Luzon. When it entered the South China Sea and came within 800 kilometers of Hong Kong that evening, the Standby Tropical Cyclone Warning Signal was issued. The first Number 3 and later the Number 8 Tropical Cyclone Warning Signal of the year were issued on 23 July. The weather deteriorated and winds started to strengthen from the northeast in the afternoon. In the morning of 24 July, gale force winds were recorded in some parts of Hong Kong when Imbudo came closest to Hong Kong. Imbudo eventually made landfall near Yangjiang. Local weather conditions improved gradually but it remained cloudy with showers the next day. 

With the establishment of a ridge of high pressure along southern China, mainly fine and hot weather with some isolated showers returned on 26 July. Fine and hot weather persisted to the end of the month. On 31 July, waterspouts and funnel clouds were observed over the sea to the southwest of the Hong Kong International Airport.

A total of 2 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 1.3.  Monthly meteorological figures and departures from normal for July are tabulated in Table 2.