The Weather of March 2002

    March 2002 was much warmer and wetter than usual. The mean temperature of 21.5 degrees was 3.0 degrees above normal, the warmest for March.  The mean minimum temperature of 20.0 degrees, 3.5 degrees above normal, was also the highest for the month.  The monthly rainfall of 238.7 millimetres was more than three times the normal amount.  The accumulated rainfall in the first three months of the year amounted to 268.3 millimetres, nearly two times the normal figure of 138.3 millimetres for the same period.

    Apart from a few light rain patches, the weather in Hong Kong in the first five days of the month was relatively warm with sunny periods.  A cold front crossed the south China coast in the evening of 5 March, bringing cooler weather to Hong Kong.  The temperature dropped to 14.9 degrees the next morning, the lowest of the month.  The continental airstream associated with the cold front maintained generally fine weather in Hong Kong up to 12 March.  The Yellow or Red Fire Danger warning was in force for several days.

    With a maritime airstream establishing over the south China coast, clouds and rain returned on 13 March.  It remained warm and humid with mist and drizzle in the next few days until another cold front passed Hong Kong in the evening of 16 March.  Weather did not improve until 19 March when the drier air from the northeast eventually cleared the sky.    Characteristic of the weather in March, the fine weather did not last long and light rain with morning mist returned the next day.  Warm and humid conditions continued as southerly winds set in.   The afternoon temperature on 21 March rose to 27.3 degrees, the highest recorded so far this year.

    A thunderstorm bearing cold front swept across the territory in the small hours of 23 March.  The heavy rain necessitated the issuance of the Amber Rainstorm Warning, the earliest rainstorm warning in the year since the revised rainstorm warning system came into effect in 1998.

    The rain continued for the next few days, though with much reduced intensity.   Very humid conditions persisted, setting the scene for development of mist and fog.   The lowest visibility occurred on 28 March when it fell to 600 metres between 4 and 5 a.m. at the Observatory.

    In the evening of 29 March, an active cold front brought another episode of thunderstorms and heavy rain to Hong Kong.  It remained cloudy with rain for the rest of the month.

    Mitag 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 Tables 1.1-1.4.  Monthly meteorological figures and departures from normal of March are tabulated in Table 2.