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Monthly Meteorological Normals for Hong Kong (1991-2020)


Table 1. Monthly mean numbers of days with tropical cyclone warning signals and Strong Monsoon Signal in Hong Kong between 1991-2020
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Month
Number of Days with
Tropical Cyclone Warning Signal
Number of Days with
Strong Monsoon Signal
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No. 1 and/or
higher
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No. 3 and/or
higher
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No. 8 and/or
higher
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No. 9 and/or
No. 10
January - - - - 3.63
February - - - - 3.90
March - - - - 4.93
April 0.20 0.13 - - 2.37
May 0.27 0.13 0.03 - 1.50
June 2.00 1.00 0.27 0.03 0.90
July 3.13 1.53 0.53 0.10 0.90
August 4.17 1.90 0.80 0.17 0.37
September 3.83 1.87 0.67 0.10 2.03
October 1.70 0.73 0.13 - 4.10
November 0.57 0.13 - - 4.30
December - - - - 5.13
Year 15.87 7.43 2.43 0.40 34.07

Figure 1.1. Monthly mean number of days with tropical cyclone warning signals in Hong Kong between 1991-2020

Figure 1.1. Monthly mean number of days with tropical cyclone warning signals in Hong Kong between 1991-2020


Figure 1.2. Monthly mean number of days with Strong Monsoon Signal in Hong Kong between 1991-2020

Figure 1.2. Monthly mean number of days with Strong Monsoon Signal in Hong Kong between 1991-2020

Table 2. Monthly mean of rainfall in Hong Kong between 1991-2020
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Month
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Total
(mm)
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Duration
(hours)
Number of Days with
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0.1 mm
or more
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25 mm
or more
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50 mm
or more
January 33.2 55 5.70 0.43 0.00
February 38.9 87 7.97 0.33 0.07
March 75.3 108 10.50 0.77 0.30
April 153.0 98 11.37 1.87 0.87
May 290.6 112 15.37 3.93 1.63
June 491.5 118 19.33 6.03 2.90
July 385.8 93 18.43 4.83 2.10
August 453.2 103 17.50 5.83 2.63
September 321.4 77 14.90 3.77 1.97
October 120.3 50 7.83 1.33 0.77
November 39.3 45 5.70 0.40 0.13
December 28.8 48 5.30 0.17 0.03
Year 2431.2 993 139.90 29.70 13.40

Figure 2. Monthly mean of rainfall in Hong Kong between 1991-2020

Figure 2. Monthly mean of rainfall in Hong Kong between 1991-2020

Table 3. Monthly mean numbers of days with lightning,thunderstorm and fog reported at the Observatory between 1991-2020
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Month
Number of Days with
Lightning
Number of Days with
Thunderstorm
Number of Days with Fog
(Visibility < 1000 m)
January 0.23 0.23 0.20
February 0.60 0.60 1.10
March 1.53 1.37 1.47
April 3.77 3.13 0.83
May 7.70 5.87 0.07
June 10.70 8.13 -
July 10.80 7.97 -
August 11.53 8.90 -
September 7.07 5.07 -
October 1.17 0.83 -
November 0.23 0.17 -
December 0.03 - 0.03
Year 55.37 42.27 3.70

Figure 3. Monthly mean numbers of days with lightning, thunderstorm and fog reported at the Observatory between 1991-2020

Figure 3. Monthly mean numbers of days with lightning, thunderstorm and fog reported at the Observatory between 1991-2020

Table 4. Monthly means of daily maximum, mean and minimum temperature recorded at the Observatory between 1991-2020
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Month
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Mean Daily
Maximum
(deg. C)
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Mean
(deg. C)
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Mean Daily
Minimum
(deg. C)
January 18.7 16.5 14.6
February 19.4 17.1 15.3
March 21.9 19.5 17.6
April 25.6 23.0 21.1
May 28.8 26.3 24.5
June 30.7 28.3 26.5
July 31.6 28.9 26.9
August 31.3 28.7 26.7
September 30.5 27.9 26.1
October 28.1 25.7 23.9
November 24.5 22.2 20.3
December 20.4 18.2 16.2
Year 26.0 23.5 21.6

Figure 4. Monthly means of daily maximum, mean and minimum temperature recorded at the Observatory between 1991-2020

Figure 4. Monthly means of daily maximum, mean and minimum temperature recorded at the Observatory between 1991-2020

Table 5. Monthly means of relative humidity, dew point temperature, wet-bulb temperature and vapour pressure recorded at the Observatory between 1991-2020
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Month
Relative Humidity (%) Dew Point
Temperature
(deg. C)
Wet-bulb
Temperature
(deg. C)
Vapour
Pressure
(hPa)
Mean Mean at
0200 hours
Mean at
1400 hours
January 74 78 67 11.7 14.0 14.2
February 79 83 72 13.2 15.0 15.7
March 82 86 75 16.1 17.5 18.7
April 83 87 75 19.7 20.9 23.4
May 83 87 76 23.0 24.0 28.2
June 82 86 76 24.9 25.9 31.6
July 81 85 74 25.2 26.3 32.1
August 81 86 74 25.1 26.1 31.8
September 78 82 71 23.6 25.0 29.4
October 73 77 65 20.2 22.2 24.1
November 72 77 65 16.7 19.0 19.6
December 70 75 63 12.4 15.1 15.0
Year 78 82 71 19.3 20.9 23.7

Figure 5.1. Monthly mean of relative humidity recorded at the Observatory between 1991-2020

Figure 5.1. Monthly mean of relative humidity recorded at the Observatory between 1991-2020


Figure 5.2. Monthly means of dew point temperature, web-bulb temperature and vapour pressure recorded at the Observatory between 1991-2020

Figure 5.2. Monthly means of dew point temperature, web-bulb temperature and vapour pressure recorded at the Observatory between 1991-2020

Table 6. Monthly means of cloud amount observed at the Observatory and sunshine duration and daily global solar radiation recorded at King's Park between 1991-2020
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Month
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Cloud Amount
(%)
Bright Sunshine blank space
Daily Global
Solar Radiation
(MJ/m2)
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Duration
(hours)
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Percentage
of Possible
January 62 145.8 43 10.55
February 72 101.7 32 10.24
March 77 100.0 27 10.71
April 77 113.2 30 12.52
May 76 138.8 34 14.46
June 77 144.3 36 14.61
July 72 197.3 48 17.22
August 70 182.1 46 15.73
September 66 174.4 47 14.99
October 58 197.8 55 14.52
November 58 172.3 52 12.26
December 57 161.6 48 10.91
Year 68 1829.3 41 13.23

Figure 6.1. Monthly mean of cloud amount recorded at the Observatory between 1991-2020

Figure 6.1. Monthly mean of cloud amount recorded at the Observatory between 1991-2020


Figure 6.2. Monthly mean of sunshine duration recorded at King's Park between 1991-2020

Figure 6.2. Monthly mean of sunshine duration recorded at King's Park between 1991-2020


Figure 6.3. Monthly mean of daily global solar radiation recorded at King's Park between 1991-2020

Figure 6.3. Monthly mean of daily global solar radiation recorded at King's Park between 1991-2020

Table 7. Monthly means of prevailing wind direction and mean wind speed recorded at the Observatory and Waglan Island between
1991-2020
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Month
Observatory Waglan Island
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Prevailing Wind
Direction
(deg.)
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Mean Wind
Speed (km/h)
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Prevailing Wind
Direction
(deg.)
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Mean Wind
Speed (km/h)
January 090 9.4 60 25.1
February 090 10.7 60 24.2
March 090 11.1 60 23.0
April 090 9.7 70 20.5
May 090 9.3 80 19.8
June 260 9.2 220 21.6
July 260 9.9 230 21.3
August 260 9.1 230 18.8
September 090 10.1 80 21.4
October 090 10.6 80 26.3
November 090 9.9 70 26.6
December 090 9.2 10 26.4
Year 090 9.9 70 22.9

Figure 7. Monthly means of prevailing wind direction and mean wind speed recorded at the Observatory and Waglan Island between 1991-2020

Figure 7. Monthly means of prevailing wind direction and mean wind speed recorded at the Observatory and Waglan Island between 1991-2020

Table 8. Monthly mean of atmospheric pressure recorded at the Observatory between 1991-2020
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Month
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Mean (hPa)
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Mean Diurnal
Range (hPa)
January 1020.1 4.5
February 1018.7 4.5
March 1016.1 4.7
April 1013.0 4.3
May 1009.3 3.8
June 1006.1 3.5
July 1005.6 3.7
August 1005.2 4.0
September 1008.8 3.9
October 1014.0 3.9
November 1017.3 4.2
December 1020.1 4.4
Year 1012.9 4.1

Figure8. Monthly mean of atmospheric pressure recorded at the Observatory between 1991-2020

Figure8. Monthly mean of atmospheric pressure recorded at the Observatory between 1991-2020

Table 9. Monthly means of sea surface temperature recorded at North Point and Waglan Island, and evaporation and potential evapotranspiration recorded at King's Park between 1991-2020
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Month
Sea Surface Temperature (deg. C) Evaporation
(mm)
Potential
Evapotranspiration
(mm)
North Point Waglan Island
0700 hours 1400 hours 0700 or
1100 hours
1400 or
1700 hours
January 17.6 17.9 17.7 17.9 69.1 59.2
February 17.0 17.3 17.0 17.2 60.4 54.7
March 18.3 18.7 18.4 18.6 73.2 66.3
April 21.4 21.8 21.3 21.7 87.2 80.3
May 24.7 25.2 24.7 25.2 109.8 95.4
June 26.6 27.0 26.6 27.0 113.8 96.5
July 26.5 27.0 26.5 27.0 142.0 113.8
August 26.6 27.0 26.8 27.2 129.7 108.6
September 27.0 27.4 27.3 27.6 122.8 94.8
October 26.5 26.7 26.6 26.9 122.6 93.0
November 23.7 24.0 23.6 23.9 95.1 78.5
December 20.0 20.3 20.1 20.3 80.9 63.4
Year 23.0 23.3 23.1 23.4 1204.1 1010.8

Figure9.1. Monthly means of sea surface temperature recorded at North Point and Waglan Island between 1991-2020

Figure9.1. Monthly means of sea surface temperature recorded at North Point and Waglan Island between 1991-2020



Figure9.2. Monthly means of evaporation and potential evapotranspiration recorded at King's Park between 1991-2020

Figure9.2. Monthly means of evaporation and potential evapotranspiration recorded at King's Park between 1991-2020

Table 10. Monthly mean of soil temperature recorded at the Observatory between 1991-2020
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Month
0.5 m 1.0 m 1.5 m
0700 hours
(deg. C)
1900 hours
(deg. C)
0700 hours
(deg. C)
1900 hours
(deg. C)
0700 hours
(deg. C)
1900 hours
(deg. C)
January 19.1 19.0 20.7 20.7 22.0 22.0
February 19.2 19.2 20.2 20.2 21.1 21.1
March 21.3 21.3 21.5 21.5 21.7 21.7
April 23.9 23.9 23.4 23.4 23.0 23.0
May 26.8 26.8 25.9 25.9 25.0 25.1
June 28.7 28.7 27.9 28.0 27.1 27.1
July 29.8 29.7 29.1 29.1 28.3 28.3
August 29.8 29.8 29.4 29.4 28.9 28.9
September 29.5 29.4 29.4 29.3 29.0 29.0
October 27.7 27.6 28.2 28.2 28.2 28.2
November 24.8 24.7 26.0 25.9 26.6 26.6
December 21.6 21.6 23.5 23.4 24.6 24.6
Year 25.2 25.1 25.4 25.4 25.5 25.5

Monthly mean of soil temperature recorded at the Observatory between 1991-2020

Figure10. Monthly mean of soil temperature recorded at the Observatory between 1991-2020

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