The Weather of August 2001

    The weather of August 2001 was warmer and drier than usual. The mean temperature of 29.2 degrees was 0.8 degrees above normal and ranked the fourth highest for August. The monthly rainfall of 318.9 millimetres was 19 per cent below the normal figure of 391.4 millimetres. However, the accumulated rainfall since 1 January amounted to 2468.9 millimetres, 45 per cent above the normal figure of 1707.4 millimetres and ranked the eighth highest for the same period.

    A trough of low pressure over the south China coast brought heavy rain and squally thunderstorms to Hong Kong on the first two days of the month. Over 100 millimetres of rainfall were recorded in Sha Tin, Tai Po and the western part of Hong Kong Island on 2 August. Temperatures fell to a minimum of 24.3 degrees in heavy rain, the lowest in the month. Rain eased off on 3 August as the trough dissipated.

    Under the influence of a ridge of high pressure over southeastern China, the weather of Hong Kong became fine on 4 August. Apart from some showers, fine and hot weather prevailed till 9 August.

    A tropical depression over the northern part of the South China Sea intensified into a tropical storm on 10 August and was named Usagi. Its outer rainbands brought thundery showers to Hong Kong. Under the combined effect of the ridge of high pressure over southeastern China and Usagi, local winds strengthened briefly in the afternoon. Rain eased off the next afternoon after Usagi moved westwards away from Hong Kong.

    On 12 August, an area of rain and thunderstorms developed rapidly over Guangdong and moved south to affect Hong Kong in the evening. Temperatures again fell to 24.3 degrees in heavy rain.

    The weather became mainly fine on 13 August. Apart from isolated thunderstorms, mainly fine weather continued the next three days. Under light northerly winds, visibility over the western part of the territory dropped to below 5000 metres in haze on the morning of 17 August.

    The weather remained mainly fine apart from isolated thunderstorms on 18 August. A hiker was killed by lightning in Tuen Mun.

    There were some showers on 19 August with haze over the western part of the territory in the morning.

    Under the influence of a ridge of high pressure over southern China, the weather became fine and very hot on 20 August. Temperatures rose to a maximum of 34.0 degrees on 23 August, the highest in the month. Sunny and very hot weather persisted till 26 August.

    An area of low pressure over the northern part of the South China Sea brought squally thunderstorms to Hong Kong on 27 August. Under the combined effect of the northeast monsoon and the area of low pressure, local winds strengthened during the afternoon of 28 August. A 15-year old boy was drowned at a Sai Kung beach and a fireman was washed away by strong waves and drowned while trying to save the boy.

    The area of low pressure intensified into a tropical depression on the evening of 28 August. Local winds strengthened offshore and there were heavy squally showers and thunderstorms. As the tropical depression moved westwards away from Hong Kong, winds moderated on the early morning of 30 August but heavy showers and thunderstorms continued. Over 100 millimetres of rainfall were recorded over most parts of the territory. The tropical depression intensified into a tropical storm near Hainan Island later in the evening and was named Fitow.

    The weather of Hong Kong improved with showers easing off on 31 August.

    There were altogether six tropical cyclones in the South China Sea and the western North Pacific in the month.