Monthly Meteorological Normals for Hong Kong

Monthly mean numbers of days with tropical cyclone warning signals and Strong Monsoon Signal in Hong Kong between 1961-1990
Monthly mean of rainfall in Hong Kong between 1961-1990
Monthly mean numbers of days with lightning, thunderstorm and fog reported at the Observatory between 1961-1990
Monthly means of daily maximum, mean and minimum temperature recorded at the Observatory between 1961-1990
Monthly means of relative humidity, dew point temperature, wet-bulb temperature and vapour pressure recorded at the Observatory between 1961-1990
Monthly means of cloud amount observed at the Observatory and sunshine duration and daily global solar radiation recorded at King's Park between 1961-1990
Monthly means of prevailing wind direction and mean wind speed recorded at the Observatory and Waglan Island between 1961-1990
Monthly mean of atmospheric pressure recorded at the Observatory between 1961-1990
Monthly means of sea surface temperature recorded at North Point and Waglan Island, and evaporation and potential evapotranspiration recorded at King's Park between 1961-1990
Monthly mean of soil temperature recorded at the Observatory between 1967-1996

Table 1. Monthly mean numbers of days with tropical cyclone warning signals and Strong Monsoon Signal in Hong Kong between 1961-1990

Month	Number of Days with Tropical Cyclone Warning Signal				Number of Days with Strong Monsoon Signal
Month	No. 1 and/or higher	No. 3 and/or higher	No. 8 and/or higher	No. 9 and/or No. 10	Number of Days with Strong Monsoon Signal
January	-	-	-	-	2.77
February	-	-	-	-	3.17
March	-	-	-	-	2.60
April	0.17	-	-	-	2.37
May	0.70	0.50	0.13	0.03	1.13
June	1.97	0.93	0.13	-	0.93
July	4.57	2.93	0.67	0.07	0.30
August	3.33	1.70	0.53	0.17	0.17
September	4.50	2.50	0.57	0.10	1.17
October	3.37	2.40	0.30	0.10	3.80
November	0.50	0.30	0.07	-	3.27
December	0.07	0.07	-	-	3.97
Year	19.17	11.33	2.40	0.47	25.63

Figure 1.1. Monthly mean number of days with tropical cyclone warning signals in Hong Kong between 1961-1990

Figure 1.2. Monthly mean number of days with Strong Monsoon Signal in Hong Kong between 1961-1990

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Table 2. Monthly mean of rainfall in Hong Kong between 1961-1990

Month	Total (mm)	Duration (hours)	Number of Days with
Month	Total (mm)	Duration (hours)	0.1 mm or more	25 mm or more	50 mm or more
January	23.4	41	5.63	0.10	0.00
February	48.0	69	8.93	0.43	0.03
March	66.9	89	10.07	0.60	0.27
April	161.5	82	11.13	2.20	0.97
May	316.7	92	14.93	3.40	1.93
June	376.0	86	19.23	4.23	1.97
July	323.5	67	17.47	3.93	1.97
August	391.4	73	17.30	4.70	2.17
September	299.7	68	14.37	3.57	1.63
October	144.8	48	8.60	1.50	0.87
November	35.1	37	5.87	0.40	0.10
December	27.3	31	3.87	0.23	0.10
Year	2214.3	782	137.40	25.30	12.00

Figure 2. Monthly mean of rainfall in Hong Kong between 1961-1990

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Table 3. Monthly mean numbers of days with lightning, thunderstorm and fog reported at the Observatory between 1961-1990

Month	Number of Days with Lightning	Number of Days with Thunderstorm	Number of Days with Fog (Visibility < 1000 m)
January	0.17	0.10	0.43
February	0.63	0.60	1.27
March	1.93	1.83	2.37
April	4.40	4.00	1.67
May	6.30	4.80	0.13
June	7.27	5.20	-
July	7.10	5.03	-
August	10.17	6.93	-
September	6.67	3.93	-
October	1.23	0.87	-
November	0.17	0.17	-
December	-	-	-
Year	46.03	33.47	5.87

Figure 3. Monthly mean numbers of days with lightning, thunderstorm and fog reported at the Observatory between 1961-1990

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Table 4. Monthly means of daily maximum, mean and minimum temperature recorded at the Observatory between 1961-1990

Month	Mean Daily Maximum (deg. C)	Mean (deg. C)	Mean Daily Minimum (deg. C)
January	18.6	15.8	13.6
February	18.6	15.9	13.9
March	21.3	18.5	16.5
April	24.9	22.2	20.2
May	28.7	25.9	23.9
June	30.3	27.8	25.9
July	31.5	28.8	26.6
August	31.3	28.4	26.3
September	30.3	27.6	25.5
October	27.9	25.2	23.1
November	24.2	21.4	19.2
December	20.5	17.6	15.4
Year	25.7	23.0	20.9

Figure 4. Monthly means of daily maximum, mean and minimum temperature recorded at the Observatory between 1961-1990

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Table 5. Monthly means of relative humidity, dew point temperature, wet-bulb temperature and vapour pressure recorded at the Observatory between 1961-1990

Month	Relative Humidity (%)			Dew Point Temperature (deg. C)	Wet-bulb Temperature (deg. C)	Vapour Pressure (hPa)
Month	Mean	Mean at 0200 hours	Mean at 1400 hours	Dew Point Temperature (deg. C)	Wet-bulb Temperature (deg. C)	Vapour Pressure (hPa)
January	71	76	62	10.2	13.0	13.1
February	78	82	70	11.8	13.8	14.5
March	81	85	73	15.0	16.5	17.6
April	83	88	75	19.0	20.2	22.4
May	83	87	76	22.6	23.7	27.7
June	82	86	76	24.4	25.4	30.7
July	80	85	73	24.9	26.0	31.6
August	81	86	74	24.8	25.9	31.4
September	78	83	71	23.3	24.6	28.8
October	73	78	66	19.8	21.8	23.6
November	69	74	61	15.2	17.9	18.0
December	68	73	59	11.2	14.3	14.1
Year	77	82	70	18.6	20.3	22.8

Figure 5.1. Monthly mean of relative humidity recorded at the Observatory between 1961-1990

Figure 5.2. Monthly means of dew point temperature, web-bulb temperature and vapour pressure recorded at the Observatory between 1961-1990

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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 1961-1990

Month	Cloud Amount (%)	Bright Sunshine		Daily Global Solar Radiation (MJ/m²)
Month	Cloud Amount (%)	Duration (hours)	Percentage of Possible	Daily Global Solar Radiation (MJ/m²)
January	58	152.4	45	11.63
February	73	97.7	30	10.69
March	76	96.4	26	11.24
April	78	108.9	29	13.14
May	74	153.8	38	16.12
June	75	161.1	40	16.55
July	65	231.1	56	19.15
August	66	207.0	52	17.61
September	63	181.7	49	16.49
October	56	195.0	54	15.46
November	53	181.5	55	13.39
December	49	181.5	54	12.03
Year	65	1948.1	44	14.46

Monthly mean of cloud amount recorded at the Observatory between 1961-1990

Figure 6.1. Monthly mean of cloud amount recorded at the Observatory between 1961-1990

Figure 6.2. Monthly mean of sunshine duration recorded at King's Park between 1961-1990

Figure 6.2. Monthly mean of sunshine duration recorded at King's Park between 1961-1990

Figure 6.3. Monthly mean of daily global solar radiation recorded at King's Park between 1961-1990

Figure 6.3. Monthly mean of daily global solar radiation recorded at King's Park between 1961-1990

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Table 7. Monthly means of prevailing wind direction and mean wind speed recorded at the Observatory and Waglan Island between 1961-1990

Month	Observatory		Waglan Island
Month	Prevailing Direction (deg.)	Mean Wind Speed (km/h)	Prevailing Direction (deg.)	Mean Wind Speed (km/h)
January	090	11.2	070	24.0
February	090	11.9	070	23.8
March	090	12.6	070	22.1
April	090	11.7	080	19.7
May	090	10.6	090	19.2
June	090	10.4	090	21.6
July	260	10.1	230	20.0
August	090	9.4	090	18.5
September	090	10.7	090	21.9
October	090	12.2	090	27.6
November	090	11.0	080	27.2
December	090	10.5	080	25.5
Year	090	11.0	080	22.6

Figure 7. Monthly means of prevailing wind direction and mean wind speed recorded at the Observatory and Waglan Island between 1961-1990

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Table 8. Monthly mean of atmospheric pressure recorded at the Observatory between
1961-1990

Month	Mean (hPa)	Mean Diurnal Range (hPa)
January	1020.2	4.1
February	1018.7	4.1
March	1016.2	4.2
April	1013.1	3.8
May	1009.1	3.4
June	1006.0	3.0
July	1005.3	3.4
August	1005.1	3.5
September	1008.8	3.6
October	1014.0	3.6
November	1017.9	3.8
December	1020.2	4.0
Year	1012.9	3.7

Figure8. Monthly mean of atmospheric pressure recorded at the Observatory between 1961-1990

Figure8. Monthly mean of atmospheric pressure recorded at the Observatory between 1961-1990

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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 1961-1990

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	17.5	17.7	17.1	17.3	97.5	73.2
February	16.7	17.0	16.3	16.4	79.0	66.3
March	17.9	18.2	17.3	17.5	92.2	77.0
April	20.9	21.3	20.3	20.5	106.9	92.0
May	24.5	25.0	24.5	24.8	137.7	115.0
June	26.5	26.9	26.6	26.9	143.9	126.6
July	26.6	27.1	27.4	27.7	171.6	150.5
August	26.5	27.0	27.3	27.6	156.9	135.8
September	27.1	27.5	27.4	27.7	150.3	120.6
October	26.3	26.6	26.3	26.5	152.2	112.8
November	23.4	23.6	23.4	23.5	129.1	88.8
December	19.8	20.0	19.5	19.7	111.5	76.7
Year	22.8	23.2	22.8	23.0	1528.8	1235.0

* 1975 - 2004

Figure9.1. Monthly means of sea surface temperature recorded at North Point between 1975-2004 and Waglan Island between 1961-1990

Figure9.1. Monthly means of sea surface temperature recorded at North Point between 1975-2004 and Waglan Island between 1961-1990

Figure9.2. Monthly means of evaporation and potential evapotranspiration recorded at King's Park between 1961-1990

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Table 10. Monthly mean of soil temperature recorded at the Observatory between 1967-1996

Month	0.5 m		1.0 m		1.5 m
Month	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	18.9	18.9	20.5	20.6	21.7	21.7
February	18.8	18.9	19.9	20.0	20.9	20.9
March	20.4	20.5	20.7	20.7	21.1	21.1
April	23.1	23.3	22.6	22.6	22.4	22.4
May	26.5	26.7	25.5	25.5	24.8	24.8
June	28.4	28.6	27.5	27.6	26.8	26.8
July	29.9	30.0	29.0	29.1	28.3	28.3
August	30.0	30.1	29.5	29.5	29.0	29.0
September	29.6	29.7	29.4	29.4	29.1	29.1
October	27.6	27.6	28.1	28.1	28.2	28.2
November	24.4	24.4	25.7	25.6	26.4	26.3
December	20.6	20.6	22.5	22.5	23.7	23.7
Year	24.9	24.9	25.1	25.1	25.2	25.2

Figure10. Monthly mean of soil temperature recorded at the Observatory between 1967-1996

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