Weather in Hong Kong

Tropical cyclone signals run 1, 3, 8, 9 and 10. No. 1 means a cyclone is centred within about 800 km of Hong Kong and may affect the territory. No. 3 means strong wind near sea level, sustained 41 to 62 km/h with gusts that may exceed 110 km/h. No. 8, issued in four directional variants, means gale or storm force wind, sustained 63 to 117 km/h from the quarter indicated with gusts that may exceed 180 km/h. No. 9 means that gale or storm force wind is increasing or expected to increase significantly. No. 10 means hurricane force, sustained 118 km/h or above with gusts that may exceed 220 km/h.

The Observatory makes a pre-No. 8 special announcement when the No. 8 signal is expected within two hours. Once No. 8 replaces No. 3, winds are normally expected to reach gale force generally in Hong Kong within 12 hours. That announcement is your cue to start moving back, not to order another drink.

At No. 9 or No. 10 all precautions should already be complete: stay indoors and away from exposed windows and doors to avoid flying debris, and beware of changes in wind direction.

Rainstorm warnings are separate and colour coded: amber is rain exceeding 30 mm in an hour, red exceeding 50 mm, black exceeding 70 mm, in each case fallen or expected generally over Hong Kong and likely to continue. Under black, the advice is to stay indoors or take shelter in a safe place until the heavy rain has passed, and for outdoor workers to stop work and take shelter.

A signal is not an airport closure. The Observatory states that aircraft operations do not depend on tropical cyclone signals, and that in respect of wind they are mainly affected by crosswinds, windshear and turbulence rather than wind speed itself. It tells the travelling public to check the latest flight information and transport conditions to and from the airport before setting out.