Climate
Hong Kong's climate is sub-tropical, tending towards the
temperate for nearly half the year. During November and
December, there are pleasant breezes, plenty of sunshine and
comfortable temperatures. Many people regard these as the
best months of the year.
January and February are cloudier, with occasional cold fronts
followed by dry northerly winds. Temperatures can drop
below 10 degrees Celsius in urban areas but sub-zero
temperatures and frost usually occur on high ground and in
the New Territories.
March and April can be very pleasant with occasional spells of
high humidity. Fog and drizzle can sometimes disrupt air
traffic and ferry services because of reduced visibility.
May to August are hot and humid with occasional showers
and thunderstorms, particularly during the mornings.
Afternoon temperatures often exceed 31 degrees, but at night
temperatures generally remain around 26 degrees.
Hong Kong is most likely to be affected by typhoons in
September, although tropical cyclones of varying strength are
not unusual at any time between May and November. On
average, about 31 tropical cyclones form over the western
North Pacific and the China Seas every year, and about half of
them reach typhoon strength with maximum winds of 118
kilometres per hour or more.
When a tropical cyclone is about 700 to 1 000 kilometres
south-east of Hong Kong, the weather is usually fine and
exceptionally hot, but isolated thunderstorms sometimes occur
in the evenings. If the cyclone's centre comes closer to Hong
Kong, winds will increase and rain can become heavy and
widespread. The heavy rain may last for a few days, and
subsequent landslips and flooding sometimes cause
considerably more damage than the winds.
The mean annual rainfall ranges from around 1 300 millimetres
at Waglan Island to more than 3 000 millimetres around Tai
Mo Shan. About 80 per cent of the rain falls between May and
September. August is the wettest month with an average
rainfall at the Hong Kong Observatory of 391.4 millimetres.
The driest month is January with 23.4 millimetres and it rains
on only about six days in the month.
Severe weather phenomena that can affect Hong Kong include
tropical cyclones, strong winter and summer monsoon winds,
monsoon troughs and thunderstorms with associated squalls
that are most frequent from April to September. Waterspouts
and hailstorms occur infrequently, while snow and tornadoes
are rare.
Climatological data are given in Appendix 53.
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