The Weather of April 1997

    April 1997 was cloudier than normal and the total bright sunshine duration was only 73.6 hours, the tenth lowest on record for April. There were only seven days without rain in the month with two heavy rain episodes in the first half of the month accounting for 85 per cent of the month's total rainfall of 133.2 millimetres. The accumulated rainfall since 1 January was 324.3 millimetres, eight per cent above the normal for the same period. The month was also characterized by misty weather.

    A fresh northeast monsoon brought the temperature down to 18.8 degrees, the lowest in the month, on 1 April. The weather was mainly cloudy, becoming misty the next morning. By the morning of 3 April, fog patches developed and affected the harbour.

    A weak cold front crossed the coast of Guangdong on 4 April bringing occasional heavy rain and squally thunderstorms to Hong Kong. Weather remained misty with rain patches during the next few days. A catamaran collided with a ferry in poor visibility near Shek Kwu Chau on the morning of 9 April. The master of the ferry was injured. The first episode of heavy rain occurred the next morning with a daily total rainfall of 50.2 millimetres recorded. However the weather cleared on 11 April and sunny weather prevailed for two days.

    A moist airstream brought cloudy and misty weather to Hong Kong on 13 April followed by heavy showers and thunderstorms. Daily rainfall amounted to 63.4 millimetres and floods occurred in Central and a few districts in Kowloon.

    Misty conditions persisted and a vehicle ferry collided with a catamaran in fog near the Brothers Islands on the morning of 15 April. Twenty-seven passengers were injured. The weather became fine and sunny during the day. However an area of thunderstorms swept across the northern part of the New Territories that evening and hailstones of two millimetres in diameter were reported in Sheung Shui near midnight.

    The northeast monsoon freshened early on 16 April but subsided gradually the next day. Misty weather returned and fog patches occurred again on 19 April. It remained misty the next few days but there were also sunny periods during the day on 21 and 22 April.

    The northeast monsoon brought drier air to Hong Kong on 23 April clearing the mist. Although it was cloudy again the next day, fine weather progressively took over. Temperatures rose to 29.7 degrees, the highest in the month, on 29 April.

    Thundery showers occurred on the afternoon of 30 April on the approach of a trough of low pressure.

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

    During the month, a total of 11 aircraft was diverted due to adverse weather.