Hong Kong Observatory says past July one of two hottest Julys on record
Average temperature at 29.8 degrees, the same figure as in July 2014 and 1 degree higher than usual; hot weather due to high air pressure and typhoons
With a sweltering average temperature of 29.8 degrees Celsius, the past month has become one of the two hottest Julys since the record began over 130 years ago.
The mean temperature, which is 1 degree higher than normal, is the same as the previous highest record for July logged in 2014.
The Hong Kong Observatory, describing last month’s weather as “unusually hot”, said the extreme temperature was due to high air pressure and typhoons.
The hottest day, July 9, saw the temperature reach 35.6 degrees, becoming the second hottest day on record for July.
Last month was also much drier than usual with only 175.9mm of rainfall, about half the normal amount of 376.5mm.
Other unusual weather phenomena in the month include reports of hail at Tai Po on July 30, caused by typhoon Mirinae from the South China Sea and the subsequent development of intense thunderstorms over the New Territories as the typhoon moved away towards Hainan island and northern Vietnam.
Last month started with hot weather and a mix of sunshine, showers and thunderstorms on the first five days, under the influence of an active southerly flow of air. The city then cooled down a bit on July 6, with the lowest temperature of the month, 24.7 degrees, recorded in the morning. This was due to an easterly airstream along the coastal areas of Guangdong province, bringing heavy rain and thunderstorms.
Super Typhoon Nepartak then headed for Taiwan on July 7 and landed at Fujian two days later, leading to sunny and very hot weather in Hong Kong during the period as the city was outside the typhoon’s circulation and was affected by the subsiding air.
Due to intense heat transfer in the air over inland Guangdong on the afternoon of July 9, which moved to Hong Kong in the evening, thunderstorms accompanied by lightning and thunder – some 9,000 times within five hours – occurred throughout the night. “Local weather remained mostly cloudy and unsettled with occasional heavy showers and thunderstorms over the next five days,” the Observatory’s analysis reads.
With high air pressure building up over south-eastern China and the northern part of the South China Sea, a spell of “generally fine weather with rather hot conditions” set in on July 15 and lasted for over two weeks, with temperatures reaching 35 degrees on July 25. In the meantime, Mirinae was brewing over the central part of the South China Sea and eventually formed on July 26.