The Weather of February 2018

    With the persistence of an intense winter monsoon during the early part of the month, the weather of February 2018 was overall cooler than usual. The monthly mean temperature of 16.0 degrees was 0.8 degree below the normal figure of 16.8 degrees. It was also relatively dry with only 4.5 millimetres of rainfall recorded in the month, less than 10 percent of the February normal of 54.4 millimetres. The accumulated rainfall for the first two months of the year was 66.7 millimetres, about 15 percent below the normal figure of 78.9 millimetres for the same period.

    An intense winter monsoon that started to affect the south China coastal areas in late January continued its dominance into the early part of February. Cold weather persisted till 8 February, with the lowest temperature of the month, 6.8 degrees, recorded at the Hong Kong Observatory on 1 February and frost being reported in places over the territory during the period as well. Following the arrival of a cold but dry continental airstream on 5 February, the initially cloudy conditions gave way to sunny skies the next day and daytime relative humidity dropped to 40 percent or below on 5 – 7 February.

    Apart from a couple of cloudy interludes on 7 and 9 February, generally fine weather persisted till 13 February. Temperatures started to climb during the period as the winter monsoon moderated, but a replenishment of northerly winds soon brought another cold snap on 12 February. Approaching the Chinese New Year festive period, the winter monsoon finally loosened its grip and moister air of maritime origin started to move in towards the south China coast. This led to increased cloudiness at first but as temperatures rose, a sunny and mild day greeted the first day of Chinese New Year on 16 February.

    After some morning fog on 17 February, a freshening easterly airstream brought cloudy and cooler weather to Hong Kong. As the easterly winds moderated, a warm maritime airstream returned to the coastal areas of Guangdong on 19 February and temperatures over most parts of the territory rose to 25 degrees or above on 20 February. Meanwhile, generally cloudy conditions persisted and with a replenishment of the winter monsoon coming down the coast of southeastern China, the weather in Hong Kong turned cooler again on 21 February. This was followed by the setting in of a fresh northerly airstream that brought overcast skies with rain patches and led to temperatures falling further over the next couple of days.

    As the winter monsoon subsided, two days of relatively mild and brighter weather followed on 24 and 25 February. Under the influence of a fresh easterly airstream, the weather then turned generally cloudy and cooler again the next day. As the easterly winds moderated, it became warm with sunny periods on 27-28 February. Temperatures at the Hong Kong Observatory climbed to the month’s highest of 26.2 degrees on the last day of the month.