The Weather of May 2000

    May 2000 was warmer and drier than usual. The mean minimum temperature and the mean temperature were 0.6 degrees and 0.2 degrees above normal respectively. Under the influence of a ridge of high pressure, prolonged periods of sunshine brought very hot weather to Hong Kong on the last three days of the month. The Very Hot Weather Warning was issued on 29 May for the first time. The monthly total rainfall was 208.3 millimetres only, 108.4 millimetres below the normal figure. However, the accumulated rainfall since 1 January amounted to 894.8 millimetres, 45 per cent above the normal figure of 616.5 millimetres for the same period.

    The month started hot with sunny periods on 1 May. Thundery showers began to affect the territory in the late evening as a trough of low pressure lingered over the south China coast. Heavy rain brought more than 100 millimetres of rainfall to Hong Kong Island and parts of Lantau Island on 2 May. There were altogether eight landslips and 16 reports of flooding. A boy was slightly injured in a landslip. The main road on the Peak subsided and was closed. Winds turned to easterly and the weather became cooler.

    It remained cloudy with some showers on 3 May and temperatures dropped to a minimum of 20.6 degrees, the lowest in the month.

    Cloud began to disperse the next day and it became sunny in the afternoon. Generally fine weather then continued for about a week till 10 May when another trough of low pressure brought in heavy rain. The rain eased off on 11 May. Clouds thinned out the next day and there were sunny periods in the afternoon. Sunny and hot weather lasted for the next few days. Under abundant sunshine, temperatures of over 34 degrees were recorded in the northern part of the New Territories on 16 May.

    As a trough of low pressure developed over south China, cloudier weather set in on 17 May. It stayed cloudy with sunny intervals apart from some light rain patches for the next few days.

    Rainbands associated with another trough of low pressure over the northern part of the South China Sea brought unsettled weather to Hong Kong on the evening of 24 May. There were isolated thunderstorms and heavy rain in the early morning the next day. Rain eased off in the afternoon and there were periods of sunshine.

    Weather turned fine and hot apart from a few isolated showers on 26 May, and hot weather prevailed for the rest of the month. With prolonged periods of sunshine, temperatures of over 34 degrees were recorded in the northern part of the New Territories on the last three days of the month. At the Observatory, the maximum temperature of 32.4 degrees recorded on 31 May was the highest in this month.

    Three tropical cyclones occurred in the South China Sea and the western North Pacific in the month.

    During the month, no aircraft was diverted due to adverse weather.