| 1. | This web page utilizes Geographic Information System (GIS) platform to display different weather observations taken at various weather stations over Hong Kong. The displayed weather elements include air temperatures, relative humidities, maximum air temperatures, minimum air temperatures, past 24-hour temperature difference, grass temperatures, visibilities, maximum gusts, mean sea level pressures, winds as well as weather photos. Radar imageries, lightning locations and hourly mean ambient gamma radiation dose rate can also be overlaid simultaneously on the map. |
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| Overview of the GIS platform regional weather web page | |
| 2. | By clicking on any of the weather stations on the map, you can obtain further information of weather observations taken at the site. Please note that : | |
| (i) | Readings of air temperature, relative humidity, maximum temperature, minimum temperature, grass temperature, visibility, maximum gust, mean sea level pressure and wind are updated every 10 minutes; | |
| (ii) | Readings of grass temperature are available between 5 p.m. and 8 a.m. on the next day; and | |
| (iii) | A picture is taken every 5 minutes. Animation normally displays photos taken during the past 6 hours. | |
In addition to these weather observations, radar imageries, locations of cloud-to-ground lightning and hourly mean ambient gamma radiation dose rate can also be overlaid on the map. 64 km radar imageries are updated every 6 minutes, 128 km and 256 km radar imageries are updated every 12 minutes, the lightning locations are updated every 5 minutes, the hourly mean ambient gamma radiation dose rate are updated every hour. By clicking on the radiation monitoring stations on the map, you can also obtain time series of ambient gamma radiation dose rate taken at the site. |
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| 3. | User Tips and Advices | |
| 3.1 | For smartphone or tablet users | |
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| 3.2 | Checking the weather condition at your location or destination | |
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| 3.3 | Choice for different weather scenarios | |
| (1) Hot and Cold Seasons : You may wish to check the daily maximum and minimum temperatures of different regions over Hong Kong. | ||
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| (2) Tropical Cyclones and Monsoons : You may wish to check the maximum gust and wind conditions over Hong Kong. | ||
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| (3) Heavy Rain and Thunderstorms : | ||
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| 3.4 | Other features | |
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| 3.5 | Other information | |
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| 4. | Points to note | |
| 4.1 | Weather information, radar imageries and lightning locations may not be synchronized. | |
| 4.2 | From readings taken at various locations in Hong Kong in the past, the hourly mean ambient gamma radiation dose rate may vary between 0.06 and 0.3 microsievert per hour. (1 microsievert = 0.000001 sievert = 0.001 millisievert). Temporal variations are generally caused by changes in meteorological conditions such as rainfall, wind and barometric pressure. Spatial variations are generally caused by differences in the radioactive content of local rock and soil. The Observatory achieved ISO 9001:2008 certification for the provision of ambient gamma radiation level measurement service in October 2015. The service was further accredited with ISO 9001:2015 certification in August 2018. | |
| 4.3 | To achieve a better presentation for weather information and to avoid overlapping of weather information, the number of weather station being displayed on the map varies with the magnification scale of the map. | |
| 4.4 | The background geographical information on this page comes from OpenStreetMap and the usage is subject to OpenStreetMap's License Terms. The downloading speed depends on the responsiveness of its servers and sometimes it may take a longer time to complete the download. | |
| 4.5 | ||
| 4.6 | The photographs are captured by webcams automatically and are compressed onsite before transmitted to the Hong Kong Observatory Headquarters. Due to limited image resolution and possible effect of environmental factors other than weather on image quality, these photographs should be used for reference only. | |
| 4.7 | When the anemometer of Chek Lap Kok is under maintenance, wind data of Chek Lap Kok may be temporarily provided by another wind station within the Hong Kong International Airport. | |
| 4.8 | The lightning information displayed above is provisional. Only limited data validation has been carried out. | |
| 5. | Explanation of symbols used on the map : | |
| General | ||
「 」 |
Station higher than 500 metres above mean sea level | |
「 」 |
Weather Photo | |
「 」 |
Today's Maximum Temperature | |
「 」 |
Today's Minimum Temperature | |
| 「※」 | Grass Temperature | |
| 「*」 | Derived from incomplete data set | |
| 「M」 | Under Maintenance/Data Temporarily Not Available | |
| Wind | ||
| 「VRB」 | Variable | |
「 」 |
Calm | |
「 」 |
Easterly wind of 18 km h-1 | |
「 」 |
Easterly wind of 90 km h-1 | |
「 」 |
Community Weather Information Network (Co-WIN) | |
| station is shown in purple | ||
| Button | ||
「 / 」 |
Show or hide legend | |
「 」 |
Refresh data | |
| Important Notice | Private Policy