Yesterday's Weather and Radiation Level

Bulletin issued at 00:15 HKT 22/Jul/2025

HKO Readings & Radiation level

Yesterday's Weather and Radiation Level:
------------------------------------------------------

Hong Kong Observatory
Maximum Air Temperature                     27.9 C
Minimum Air Temperature                     26.4 C
Grass Minimum Temperature                   26.2 C
Relative Humidity                        90 - 96 Percent
Rainfall                                    42.4 mm 
Total rainfall since 1st January           807.4 mm
Against an average of                     1337.3 mm

Other Stations                Min                  Max
King's Park                  25.8 C               27.6 C
Wong Chuk Hang               25.7 C               27.9 C
Ta Kwu Ling                  26.0 C               28.5 C
Lau Fau Shan                 25.3 C               28.7 C
Tai Po                       26.0 C               27.8 C
Sha Tin                      26.1 C               29.0 C
Tuen Mun                     25.5 C               27.8 C
Tseung Kwan O                25.4 C               27.7 C
Sai Kung                     26.0 C               27.9 C
Cheung Chau                  24.5 C               26.8 C
Chek Lap Kok                 26.6 C               29.3 C
Tsing Yi                     25.7 C               28.4 C
Shek Kong                    26.1 C               29.2 C
Tsuen Wan Ho Koon            24.8 C               26.7 C
Tsuen Wan Shing Mun Valley   25.7 C               27.9 C
Hong Kong Park               25.7 C               28.1 C
Shau Kei Wan                 24.8 C               27.0 C
Kowloon City                 25.4 C               28.2 C
Happy Valley                 26.2 C               29.4 C
Wong Tai Sin                 25.9 C               28.7 C
Stanley                      25.3 C               27.7 C
Kwun Tong                    25.5 C               28.2 C
Sham Shui Po                 26.0 C               28.8 C
Kai Tak Runway Park          25.5 C               28.3 C
Yuen Long Park               25.8 C               29.0 C

Duration of sunshine (King's Park):              0.0 H
The mean UV index recorded at King's Park yesterday was 1,
the UV intensity was LOW.
The maximum UV index for yesterday was 3.
Sea Surface Temperature (Waglan Island):        24.2 C
Yesterday's (21 Jul 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                             0.09
Kat O                               0.10
Yuen Ng Fan                         0.11
Tai Mei Tuk                         0.12
Sha Tau Kok                         0.10
Kwun Tong                           0.13
Sai Wan Ho                          0.09
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.