The Weather of June 2004

    The weather of June 2004 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 total bright sunshine duration of 205.3 hours was about 27 percent above normal. It was also drier than usual with a monthly rainfall of 144.7 millimetres, about 62 percent below normal. The accumulated rainfall since the beginning of the year was 693.4 millimetres, 30 percent below normal for the same period. The mean relative humidity of only 78 percent was also equal to the lowest record for June set in 1967, 1988 and 2000.

    With a ridge of high pressure covering southeastern China, it was mainly fine and hot in Hong Kong in the first day of June 2004. There were sunny periods and isolated showers in the following 5 days. On 6 June, it became overcast with rain when a trough of low pressure edged close to Hong Kong. It remained cloudy with some showers in the next two days.

    On 8 June, the Standby Signal No. 1 was issued the first time this year to warn the public of Typhoon Conson in the South China Sea. Conson eventually moved northeastward away from Hong Kong the next day. There were sunny periods and some showers on 8 and 9 June.

    Fine weather prevailed from 10 to 14 June as a ridge of high pressure dominated over southeastern China.

    The approach of a trough of low pressure over southern China resulted in heavy showers and thunderstorms in Hong Kong on 15 June. Over 40 millimetres of rain was recorded in parts of the Hong Kong Island and the eastern and central parts of the New Territories. The weather remained cloudy and showery on 16 June. The showers eased off and there were sunny periods on 17 June.

    Under the influence of a southwesterly airstream, the weather was sunny and hot from 18 to 20 June. The Very Hot Weather Warning was issued on 20 June, the first time in 2004. As a trough of low pressure formed over the coastal area, the weather deteriorated quickly that night with frequent thunderstorms and heavy showers. Unsettled weather continued on 21 June with over 70 millimetres of rainfall recorded in the Lantau Island.

    As the trough of low pressure dissipated, the weather improved on 22 and 23 June and there were sunny periods amidst some showers. Apart from isolated showers, the weather was generally fine and hot in the next 5 days.

    When Typhoon Mindulle moved towards the Luzon Strait on 29 June, it became very hot in Hong Kong and the maximum temperature shot up to 34.2 degrees, the highest in the month. The weather remained very hot with some showers and thunderstorms on the last day of the month.

    A total of five 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 of June are tabulated in Table 2.