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Regional Weather

Regional Weather

Look up regional temperatures, relative humidities and wind speeds by seleecting the "Weather Elements" on the Map

  • Weather Observations
    Understanding Weather Conditions
    The importance of observations

    To accurately predict the future weather, forecasters must clearly understand the present weather conditions, which are made known by way of weather observations.

    How are weather observations made?

    A weather observer is required to perform regular observations within ten minutes ending on each hour. Observations on several meteorological elements are made during this period, and a short account of each is given below:

    cloud condition
    Cloud condition

    The observers is required to record the amount of clouds, the types of clouds and the heights of different cloud layers.

    weather situation
    Weather situation

    Fog, rain and thunderstorms are examples of this meteorological element. Although observations are mainly taken within the last 10 minutes of the hour, the observer needs to pay attention to the weather situation round the clock and record any significant changes (e.g. when the rain begins).

  • Weather Observations
    Meteorological elements
    Visibility

    Visual observation is still the main method used in visibility reporting. The observer assesses the visibility by determining the longest distance at which certain objects (mountains or buildings) could still be seen.

    Temperature

    The observer reads the dry-bulb temperature (which is generally referred to as the "air temperature") and the wet-bulb temperature from a pair of thermometers. Based on the difference between these two values, dew-point temperature and relative humidity can be calculated.

    Wind

    The wind-measuring instrument contains a wind vane and an anemometer. The observer takes the mean wind direction and speed, as well as the maximum gust recorded within the observation period.

  • Weather Observations
    Meteorological elements (2)
    Atmospheric pressure

    The observer reads the station-level pressure from the barometer and then computes the mean sea-level pressure using additional information, including station height and air temperature.

    Rainfall amount

    With a specialised measuring cylinder, the observer obtains rainfall data by measuring the amount of rainwater collected in the rain-gauge.

    Where are the weather observations carried out?

    In Hong Kong, weather observations are made at the Hong Kong Observatory Headquarters in Tsim Sha Tsui and the meteorological station inside the Hong Kong International Airport.

    In addition to the core measurements already described, grass minimum temperature and soil temperatures are measured at the Headquarters, while sunshine duration, solar radiation, ultra-violent data and evaporation rate are recorded at the King's Park meteorological station.

    With the help of the North Point Fire Station officers, the Observatory also receives sea surface temperature data from Victoria Harbour everyday.