The Weather of February 2013

     Under the influence of mild easterly airstreams during most part of the month, Hong Kong experienced unseasonably warm weather in February 2013.  The monthly mean maximum temperature of 22.1 degrees and the mean temperature of 19.1 degrees were more than 2 degrees above normal and respectively the second and fourth highest on record for February.  The monthly rainfall was only 1.5 millimetres, much below the normal figure of 54.4 millimetres and ranking the tenth lowest on record for February.  The accumulated rainfall in the first two months of the year amounted to 4.9 millimetres, only about 6 percent of the normal figure of 78.9 millimetres for the same period.

     Under the influence of a dry northeast monsoon, the month started off generally fine in Hong Kong but the weather became cloudy and windy in the evening on 2 February when a fresh to strong easterly airstream set in.  While the easterly airstream moderated gradually in the afternoon on the next day, local weather remained cloudy.  Affected by a warm and humid maritime airstream, local weather was mainly cloudy with rain patches and coastal fog from 4 to 7 February.  The visibility at Waglan Island once fell to around 100 metres on 5 February.

     A cold front over southern China moved across the coastal areas of Guangdong on 8 February.  Affected by the associated intense northeast monsoon, local weather was cloudy and windy with rain patches on that day.  Temperatures during the day dropped by 5 to 6 degrees generally compared to the previous day.  The weather was cloudy and cold on 9 February with the temperature at the Observatory dropping further to a minimum of 11.9 degrees, the lowest of the month. 

     As the northeast monsoon moderated slightly, local temperatures rose gradually on 10 February.  A fresh easterly airstream prevailed over the coastal areas of Guangdong on 11 February.  Locally, with the clouds thinning out during the day, there were sunny periods in the afternoon.   Affected by a dry continental airstream, the weather was generally fine and dry on the next two days.  Under the influence of a mild easterly airstream, it turned mainly cloudy on 14 February and there were rain patches on 15 February.  Meanwhile, a cold front crossed the coast of Guangdong on the evening of 15 February.  The associated northeast monsoon brought cooler weather with a few light rain patches to Hong Kong on the next two days. 

     Warm and foggy weather returned to the territory when a humid maritime airstream affected the coastal areas of Guangdong on 18 February.  The foggy situation persisted on the morning of 19 February with the visibility in many parts of the territory falling below 500 metres.  There were sunny periods in that afternoon and the temperatures at the Observatory rose to a maximum of 26.2 degrees, the highest of the month.  With another cold front moving across the coast of Guangdong, local northeasterlies strengthened and temperatures fell significantly in that evening.  Affected by the northeast monsoon behind the cold front, it was cloudy and cool on 20 February.  With the persistence of the northeast monsoon, the weather was cool in the morning with sunny periods in the afternoon for the ensuing three days.

     Under the influence of a moderate to fresh easterly airstream, it became cloudy and windy on 24 February.  The easterlies prevailing over the coast of Guangdong abated in the next day.  Locally, there were some coastal mist in the morning.  Affected by a warm and humid maritime airstream, there were rain patches and coastal fog in the morning on 26 and 27 February.  A slightly cooler easterly airstream brought a few rain patches and coastal fog to the territory on the last day 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 February are tabulated in Table 2.