The Weather of April 2003

    April 2003 was much warmer and drier than usual. The mean temperature of 23.9 degrees was 1.7 degrees above normal. The mean minimum temperature of 22.4 degrees ranked the fourth highest on record. The monthly rainfall of 84.5 millimetres was only about half the normal figure of 161.5 millimetres. The accumulated rainfall since the beginning of the year was 159.9 millimetres, also about half the normal figure of 299.8 millimetres for the same period.

    Under the influence of a maritime airstream, the weather was cloudy with light rain patches in the first 3 days of April 2003. The rain stopped in the afternoon on 4 April after the passage of a cold front across the South China coast. Cloudy and cool conditions continued for the next 2 days.

    It became very humid with rain on 7 April. Fog patches occurred in 2 consecutive mornings. An area of active thunderstorms affected Hong Kong in the evening of 8 April and brought more than 65 millimetres of rainfall. Both the Thunderstorm Warning and the Amber Rainstorm Warning were issued for the first time this year. It remained cloudy with rain patches in the next 3 days.

    The rain ceased on 12 April and there were periods of bright sunshine for 2 days. The rain returned on 14 April as another cold front crossed the South China coast in the early morning. Temperature fell from around 27 degrees overnight to about 22 degrees during the day. It remained cool and cloudy with light rain patches for the ensuing 3 days.

    With a ridge establishing over southeast China, the weather became mainly fine during the day on 17 April. Apart from a few light rain patches, it was mainly fine with long periods of bright sunshine until 20 April.

    Light rain occurred on 21 April when a weak cold front crossed the South China coast. It became hot in the next few days as a southerly airstream replaced the northeasterly winds. With over 10 hours of bright sunshine on 24 April, the temperature rose to 29.8 degrees that afternoon, the highest in the month.

    Another weak cold front reached the South China coast on 25 April, bringing hazy conditions to Hong Kong for 2 days. There was morning mist on 27 April and on the following 2 days. It was cloudy with light rain patches on the last day of the month.

    Kujira was the only tropical cyclone which occurred in the western North Pacific in the month.

    Details of issuance and cancellation of various warnings/signals in the month are summarized in Table 1.1 to 1.4. Monthly meteorological figures and departures from normal of April are tabulated in Table 2.