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With the northeast monsoon bringing a dry continental air mass to the south China coast, the weather of January 2015 was sunnier than usual. The total duration of sunshine in the month was 198.8 hours, 39 per cent above the normal figure of 143.0 hours. The monthly mean amount of cloud was 45 per cent, against a normal figure of 61 per cent. As a result of the rain on January 12 and 13, the monthly total rainfall of 41.7 millimetres was 69 per cent above the January normal of 24.7 millimetres. Overall, the mean temperature of the month was 16.4 degrees, only 0.1 degrees above normal.
Under the influence of a dry winter monsoon, Hong Kong started off with cool and dry conditions on the first four days of the month. Affected by a mild and humid maritime airstream, it turned cloudy with mist and coastal fog on January 5. With the clouds thinning out, the weather became generally fine and warm in the afternoon of January 6. Temperatures at the Hong Kong Observatory rose to a maximum of 23.9 degrees that day, the highest of the month.
Following some morning fog early on January 7, temperatures fell during the day by 4 to 5 degrees compared with the previous day as a cold front crossed the coast of Guangdong in the morning. Subsequently affected by a dry continental air mass, mainly fine weather prevailed for the next three days.
A broad band of clouds covered southern China and brought a few rain patches to Hong Kong on January 11. The weather became cold and rainy on January 12 and 13 as an intense winter monsoon reached the south China coastal areas. Most of the rain in the month, about 40 millimetres in total, fell during the two-day period. As the broad rain band moved eastward away from the Pearl River Estuary, the rain eased off and the weather became fine in the night of January 13. Under clear night skies, it remained cold in the morning over the next two days. Temperatures at the Hong Kong Observatory fell to a minimum of 10.3 degrees early on January 14, the lowest of the month. Dominated by a dry winter monsoon, local weather remained generally fine and dry up to January 23. Relative humidity at the Hong Kong Observatory dropped below 40 per cent on January 19 and 22.
Affected by a humid easterly airstream, the weather turned mainly cloudy with light rain and mist patches on January 24 and 25. After a fine and relatively mild day on January 26, a strengthening of the easterly winds brought windy and slightly cooler weather to the territory over the next three days. The weather turned cloudier again as a cold front approached the south China coast on January 30, and temperatures dropped further the next day with some light rain patches.
One tropical cyclone occurred over the South China Sea and the western North Pacific in the month.
Details of issuance and cancellation of various warnings/signals in the month are summarised in Table 1. Monthly meteorological figures and departures from normal for January are tabulated in Table 2.
Ends/Tuesday, February 3, 2015
Issued at HKT 18:10
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