Yesterday's Weather and Radiation Level

Bulletin issued at 00:15 HKT 21/May/2025

HKO Readings & Radiation level

Yesterday's Weather and Radiation Level:
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Hong Kong Observatory
Maximum Air Temperature                     30.8 C
Minimum Air Temperature                     28.3 C
Grass Minimum Temperature                   26.7 C
Relative Humidity                        71 - 83 Percent
Rainfall                                       0 mm 
Total rainfall since 1st January           142.0 mm
Against an average of                      471.4 mm

Other Stations                Min                  Max
King's Park                  27.7 C               31.1 C
Wong Chuk Hang               27.7 C               30.6 C
Ta Kwu Ling                  26.0 C               33.2 C
Lau Fau Shan                 26.5 C               33.5 C
Tai Po                       27.4 C               32.6 C
Sha Tin                      27.6 C               31.7 C
Tuen Mun                     27.1 C               31.4 C
Tseung Kwan O                26.3 C               30.8 C
Sai Kung                     27.0 C               32.8 C
Cheung Chau                  26.6 C               30.7 C
Chek Lap Kok                 26.5 C               31.3 C
Tsing Yi                     27.5 C               30.9 C
Shek Kong                    27.2 C               31.3 C
Tsuen Wan Shing Mun Valley   27.0 C               31.1 C
Hong Kong Park               27.9 C               29.7 C
Shau Kei Wan                 26.4 C               30.2 C
Kowloon City                 27.8 C               32.4 C
Happy Valley                 28.3 C               30.7 C
Wong Tai Sin                 27.7 C               31.7 C
Stanley                      27.0 C               31.5 C
Kwun Tong                    27.6 C               31.9 C
Sham Shui Po                 28.0 C               32.5 C
Kai Tak Runway Park          27.6 C               31.0 C
Yuen Long Park               27.0 C               32.3 C
Tai Mei Tuk                  26.9 C               33.6 C

Duration of sunshine (King's Park):1.4 H    
The mean UV index recorded at King's Park yesterday was 3the UV intensity was MODERATE 
The maximum UV index for yesterday was 6.
Sea Surface Temperature (Waglan Island):        27.0 C
Yesterday's (20 May 2025) average ambient gamma radiation
dose rate taken outdoors in Hong Kong ranged from 0.08 to
0.15 microsievert per hour.  These are within the normal
range of fluctuation of the background radiation level in
Hong Kong (See Note). The average dose rates measured at the
radiation monitoring stations over various parts of the
territory were as follows :

Station                     Yesterday's average
                            (microsievert/hour)
Ping Chau                           0.08
Tap Mun                             0.08
Kat O                               0.10
Yuen Ng Fan                         0.11
Tai Mei Tuk                         0.12
Sha Tau Kok                         0.10
Kwun Tong                           0.12
Sai Wan Ho                          0.08
King's Park                         0.15
Tsim Bei Tsui                       0.13
Cape D'Aguilar                      0.11
Chek Lap Kok                        0.15   


Note
1.     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)

2.     Temporal variations are generally caused by changes in
       meteorological conditions such as rainfall, wind and
       barometric pressure.

3.     Spatial variations are generally caused by differences in
       the radioactive content of local rock and soil.

4.     The data displayed is provisional. Only limited data
       validation has been carried out.

5.     The range of relative humidity in the daily weather summary
       originates from the observer's reports of Hourly
       Readings of the day. This follows the long-term practice of
       collecting climatological data of the Hong Kong Observatory
       for over a century. It may differ from the relative humidity
       range derived from the 1-minute reports of the automatic
       weather station.