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March, 2006, was marked by low visibility, humid weather and rapidly fluctuating temperatures. The mean relative humidity of 86% was 5% above normal. The number of hours of reduced visibility observed at the Hong Kong International Airport reached 277 hours (about 37% of the month), setting a new record for March since observation began in 1997. Despite the humid weather, the monthly total rainfall of 48.4 millimetres was 18.5 millimetres below the normal amount. The accumulated rainfall since the beginning of the year was 102.4 millimetres, about 26% below the normal figures of 138.3 millimetres.
Under the influence of the northeast monsoon, it was fine and cold on the first three days of March. With a broad cloud band covering southern China, local weather turned cloudy on March 4. A humid maritime airstream set in on March 5, bringing mist and rain patches to the territory. The weather remained humid with fog patches the next day. While it was foggy on the morning of March 7, sunshine streamed through the clouds during the day. Apart from the relatively low visibility, it was mild with sunny periods in the following four days.
A cold front crossed the south China coast on the evening of March 12, bringing rain patches and appreciably cooler weather to Hong Kong. It was cold with some rain in the ensuing two days. The temperature fell to 9.0 degrees on March 14, the lowest in the month. The weather stayed cloudy and cool on March 15. It became hazy as the local winds subsided on March 16, with visibility in the harbour dropping below 2000 metres at times.
Humid and foggy weather returned on March 17 when a moist easterly airstream affected the south China coast. With plenty of sunshine during the day, the temperature rose to 26.2 degrees on March 18, the highest in the month. The arrival of a northeast monsoon brought mainly cloudy weather to the territory in the next two days.
Under the influence of a maritime airstream, it was foggy on March 21 and 22. Thick fog in the harbour on the morning of March 23 reduced the visibility to about 200 metres. The weather became rainy as a rain bearing cold front moved across the coast of Guangdong that night. It was overcast with rain in the following four days.
The weather became mainly fine on March 28 and remained so for the rest of the month.
Only one tropical cyclone occurred in the western North Pacific in the month.
Details of the issuance and cancellation of various warnings/signals in the month are summarised in Table 1. Monthly meteorological figures and departures from normal of March are shown in Table 2.
Ends/Tuesday, April 4, 2006
Issued at HKT 14:00
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