The Weather of January 2013

     The weather of the first month in 2013 was characterized by plenty of sunshine and dry condition which were attributed to the prevalence of the relatively dry winter monsoon for most of the month.  The total duration of sunshine in January 2013 was 184.0 hours, 41.0 hours above the normal figure of 143.0 hours.  The total rainfall recorded in the month was only 3.4 millimetres, 21.3 millimetres below the normal figure of 24.7 millimetres.  The month was also warmer than usual.  The monthly mean temperature of 16.7 degrees was 0.4 degrees above the normal figure of 16.3 degrees.

     Under the influence of the winter monsoon, it was cold and very dry in Hong Kong on the first day of the month.  The temperatures at the Observatory fell to a minimum of 10.8 degrees in the morning, the lowest of the month.  With the winds veering to the east, temperatures over most parts of the territory rebounded on 2 January.  A replenishment of the winter monsoon arrived at the south China coastal areas on 3 January, bringing cooler weather to Hong Kong.  The weather turned cloudy and cold on 4 January.  Dominated by the dry winter monsoon, local weather was generally fine and cool with some haze for the ensuing five days. 

     An extensive cloud band over southern China brought generally cloudy weather to the territory on 10 January. There were sunny periods with haze for the next two days.   Affected by a dry continental airstream, it was sunny on 13 and 14 January.  A cloud band over the south China coastal areas brought cloudy weather to Hong Kong on 15 January.  With the clouds thinning out, it turned fine and dry the next day. 

     A replenishment of the winter monsoon reached the south China coast on 17 January.  Locally, it was fine and dry with winds freshening from the north in the afternoon.  Temperatures over most parts of the territory were 2 to 3 degrees lower than those of the previous day.  With the prevalence of the winter monsoon, it remained fine and dry on 18 and 19 January. 

     Under the influence of a relatively mild easterly airstream, local weather became warmer on 20 January and the ensuing two days.  The temperatures at the Observatory rose to a maximum of 25.6 degrees on 22 January, the highest of the month.  A weak replenishment of the winter monsoon brought slightly cooler weather with relative low visibility from 23 to 25 January.  Affected by a rainband over the south China coastal areas, there were a few mist and rain patches on the next two days.  With the return of the dry northeast monsoon, local weather became generally fine and dry on 28 and 29 January.  Under the influence of a fresh easterly airstream, it was mainly fine and mild on the last two days of the month.

     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 summarized in Tables 1.1 to 1.3.  Monthly meteorological figures and departures from normal for January are tabulated in Table 2.