The Weather of August 2015

    August 2015 was hotter and drier than usual. The mean temperature in the month was 29.3 degrees, 0.7 degree above the normal figure of 28.6 degrees and the seventh highest for August on record. The monthly total rainfall recorded in August 2015 was 143.3 millimetres, only about one-third of the normal figure of 432.2 millimetres. The accumulated rainfall of 1531.2 millimetres since 1 January was about 20 percent below the normal figure of 1905.5 millimetres for the same period.

    With a ridge of high pressure strengthening and extending westward from the western North Pacific to southern China, August 2015 started with a spell of fine weather. With plenty of sunshine, conditions became very hot during the day with maximum temperatures exceeding 33 degrees on 3 - 7 August. As Severe Typhoon Soudelor moved across Taiwan and made landfall over Fujian, the summer heat grew even more intense on 8 - 9 August under the subsidence effect ahead of Soudelor. With northwesterly winds bringing haze and a relatively dry air mass to Hong Kong, temperatures at the Observatory soared to a maximum of 36.3 degrees on the afternoon of 8 August, an all-time high since records began in 1884.

    While it remained mostly fine and very hot during the day on 9 August, local weather also became more unsettled that night under the influence of a southwesterly airstream, with squally thunderstorms and showers bringing more than 30 millimetres of rain to many places of the territory, especially over the New Territories. Apart from a generally fine and very hot day on 12 August, showers and thunderstorms continued to affect Hong Kong on 10 - 16 August. Red rainstorm warning was issued on 15 August with more than 100 millimetres of rain recorded over the New Territories.

    The weather in Hong Kong turned fine on 17 August and it was mostly a mixture of sunshine and showers with some very hot days in the week that followed. With another typhoon Goni east of Taiwan tracking towards Japan and bringing enhanced subsidence effect and off-land flow over the south China coastal areas, daytime temperatures in Hong Kong again reached 33 degrees and higher on 24 and 25 August.

    With a trough of low pressure developing and lingering over the coast of Guangdong, the weather turned cloudier and more showery towards the end of the month.