Monthly Meteorological Normals for Hong Kong

Monthly mean numbers of days with tropical cyclone warning signals and Strong Monsoon Signal in Hong Kong between 1971-2000
Monthly mean of rainfall in Hong Kong between 1971-2000
Monthly mean numbers of days with lightning, thunderstorm and fog reported at the Observatory between 1971-2000
Monthly means of daily maximum, mean and minimum temperature recorded at the Observatory between 1971-2000
Monthly means of relative humidity, dew point temperature, wet-bulb temperature and vapour pressure recorded at the Observatory between 1971-2000
Monthly means of cloud amount observed at the Observatory and sunshine duration and daily global solar radiation recorded at King's Park between 1971-2000
Monthly means of prevailing wind direction and mean wind speed recorded at the Observatory and Waglan Island between 1971-2000
Monthly mean of atmospheric pressure recorded at the Observatory between 1971-2000
Monthly means of sea surface temperature recorded at North Point and Waglan Island, and evaporation and potential evapotranspiration recorded at King's Park between 1971-2000
Monthly mean of soil temperature recorded at the Observatory between 1971-2000

Table 3. Monthly mean numbers of days with lightning, thunderstorm and fog reported at the Observatory
between 1971-2000

Table 1. Monthly mean numbers of days with tropical cyclone warning signals and
Strong Monsoon Signal in Hong Kong between 1971-2000

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	-	-	-	-	4.33
February	-	-	-	-	4.33
March	-	-	-	-	3.83
April	0.17	0.03	-	-	3.00
May	0.43	0.27	0.07	-	1.60
June	2.23	1.23	0.20	0.03	1.17
July	4.43	2.57	0.57	0.07	0.50
August	3.93	1.67	0.60	0.13	0.17
September	4.53	2.23	0.40	0.07	1.77
October	3.17	2.03	0.20	0.07	5.30
November	0.50	0.17	0.07	-	4.83
December	0.07	0.07	-	-	5.23
Year	19.46	10.27	2.11	0.37	36.07

Figure 1.1. Monthly mean number of days with tropical cyclone warning signals in Hong Kong between 1971-2000

Figure 1.2. Monthly mean number of days with Strong Monsoon Signal in Hong Kong between 1971-2000

Figure 1.2. Monthly mean number of days with Strong Monsoon Signal in Hong Kong between 1971-2000

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Table 2. Monthly mean of rainfall in Hong Kong between
1971-2000

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	24.9	43	5.60	0.20	0.00
February	52.3	76	9.47	0.53	0.07
March	71.4	91	10.47	0.67	0.30
April	188.5	87	11.67	2.57	1.23
May	329.5	101	15.47	3.77	2.00
June	388.1	95	18.77	4.17	2.13
July	374.4	80	17.77	4.67	2.40
August	444.6	87	17.43	5.40	2.40
September	287.5	68	14.80	3.47	1.60
October	151.9	50	8.10	1.57	1.00
November	35.1	36	5.67	0.37	0.10
December	34.5	36	4.27	0.30	0.13
Year	2382.7	850	139.49	27.69	13.36

Figure 2. Monthly mean of rainfall in Hong Kong between 1971-2000

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Month	Number of Days with Lightning	Number of Days with Thunderstorm	Number of Days with Fog (Visibility < 1000 m)
January	0.13	0.10	0.23
February	1.00	0.97	1.23
March	1.77	1.63	2.30
April	4.77	4.20	1.13
May	6.67	5.27	0.17
June	7.70	5.60	-
July	8.47	5.90	-
August	11.00	8.10	-
September	6.93	4.30	-
October	1.13	0.80	-
November	0.23	0.23	-
December	-	-	0.03
Year	49.80	37.10	5.09

Figure 3. Monthly mean numbers of days with lightning, thunderstorm and fog reported at the Observatory between 1971-2000

Figure 3. Monthly mean numbers of days with lightning, thunderstorm and fog reported at the Observatory between 1971-2000

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Table 4. Monthly means of daily maximum, mean and minimum temperature recorded at the Observatory between 1971-2000

Month	Mean Daily Maximum (deg. C)	Mean (deg. C)	Mean Daily Minimum (deg. C)
January	18.6	16.1	14.1
February	18.6	16.3	14.4
March	21.5	18.9	16.9
April	25.1	22.5	20.6
May	28.4	25.8	23.9
June	30.4	27.9	26.1
July	31.3	28.7	26.7
August	31.1	28.4	26.4
September	30.2	27.6	25.6
October	27.7	25.3	23.4
November	24.0	21.4	19.4
December	20.3	17.8	15.7
Year	25.6	23.1	21.1

Figure 4. Monthly means of daily maximum, mean and minimum temperature recorded at the Observatory between 1971-2000

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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 1971-2000

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	73	78	65	11.0	13.5	13.7
February	78	82	71	12.2	14.4	14.8
March	82	86	75	15.5	17.0	18.2
April	83	88	76	19.4	20.5	22.9
May	84	88	77	22.7	23.7	27.8
June	82	86	76	24.5	25.6	30.9
July	81	85	74	25.0	26.1	31.7
August	82	86	75	24.9	25.9	31.5
September	79	83	72	23.4	24.7	28.9
October	74	78	66	19.9	21.9	23.8
November	70	75	61	15.3	17.9	18.1
December	69	74	60	11.6	14.5	14.4
Year	78	82	71	18.8	20.5	23.1

Figure 5.1. Monthly mean of relative humidity recorded at the Observatory between 1971-2000

Figure 5.2. Monthly means of dew point temperature, web-bulb temperature and vapour pressure recorded at the Observatory between 1971-2000

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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 1971-2000

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	60	141.7	42	10.55
February	73	93.8	29	9.61
March	79	89.6	24	10.18
April	80	101.8	27	11.83
May	77	138.6	34	14.35
June	76	158.3	39	15.31
July	68	214.9	52	17.52
August	69	189.7	48	16.07
September	65	171.8	47	15.14
October	57	191.1	53	14.46
November	53	178.2	54	12.64
December	51	173.3	52	11.13
Year	67	1842.9	41	13.23

Monthly Cloud Amount Observed at the Observatory between 1971-2000

Figure 6.1. Monthly mean of cloud amount recorded at the Observatory between 1971-2000

Figure 6.2. Monthly mean of sunshine duration recorded at King's Park between 1971-2000

Figure 6.2. Monthly mean of sunshine duration recorded at King's Park between 1971-2000

Figure 6.3. Monthly mean of daily global solar radiation recorded at King's Park between 1971-2000

Figure 6.3. Monthly mean of daily global solar radiation recorded at King's Park between 1971-2000

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Table 7. Monthly means of prevailing wind direction and mean wind speed recorded at the Observatory and Waglan Island between 1971-2000

Month	Observatory		Waglan Island
Month	Prevailing Direction (deg.)	Mean Wind Speed (km/h)	Prevailing Direction (deg.)	Mean Wind Speed (km/h)
January	090	11.0	070	25.4
February	090	12.1	070	25.1
March	090	12.6	070	23.5
April	090	11.7	070	21.2
May	090	10.8	080	20.2
June	090	11.0	230	23.3
July	090	10.9	230	21.9
August	090	10.2	240	20.0
September	090	11.0	090	22.8
October	090	12.4	080	28.7
November	090	10.9	080	27.9
December	090	10.3	070	26.5
Year	090	11.2	070	23.9

Figure 7. Monthly means of prevailing wind direction and mean wind speed recorded at the Observatory and Waglan Island between 1971-2000

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Table 8. Monthly mean of atmospheric pressure recorded at the Observatory between
1971-2000

Month	Mean (hPa)	Mean Diurnal Range (hPa)
January	1020.1	4.1
February	1018.6	4.2
March	1016.1	4.2
April	1012.8	3.9
May	1009.4	3.4
June	1006.2	3.2
July	1005.5	3.4
August	1005.1	3.5
September	1009.2	3.5
October	1014.0	3.6
November	1018.0	3.8
December	1020.5	4.0
Year	1013.0	3.7

Figure8. Monthly mean of atmospheric pressure recorded at the Observatory between 1971-2000

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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 1971-2000

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	17.5	17.7	80.7	57.9
February	16.7	17.0	16.6	16.7	67.6	53.0
March	17.9	18.2	17.6	17.8	78.1	63.5
April	20.9	21.3	20.7	20.9	93.2	80.0
May	24.5	25.0	24.5	24.7	118.4	98.3
June	26.5	26.9	26.6	26.9	129.0	112.7
July	26.6	27.1	27.2	27.5	155.5	131.6
August	26.5	27.0	27.1	27.4	143.2	120.9
September	27.1	27.5	27.5	27.7	134.2	99.0
October	26.3	26.6	26.4	26.6	136.4	92.8
November	23.4	23.6	23.3	23.5	112.5	74.0
December	19.8	20.0	19.7	19.9	94.5	60.8
Year	22.8	23.2	22.9	23.1	1343.4	1044.5

* 1975 - 2004

Figure9.1. Monthly Sea Surface Temperature Recorded at North Point between 1975-2004 and Waglan Island between 1971-2000

Figure9.1. Monthly Sea Surface Temperature Recorded at North Point between 1975-2004 and Waglan Island between 1971-2000

Figure9.2. Monthly means of evaporation and potential evapotranspiration recorded at King's Park between 1971-2000

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Table 10. Monthly mean of soil temperature recorded at the Observatory between 1971-2000

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	18.8	18.8	20.3	20.4	21.6	21.6
February	18.9	18.9	19.8	19.9	20.8	20.8
March	20.6	20.7	20.8	20.8	21.1	21.1
April	23.4	23.5	22.8	22.8	22.5	22.5
May	26.5	26.6	25.5	25.6	24.8	24.8
June	28.5	28.5	27.5	27.5	26.7	26.8
July	29.8	29.9	29.0	29.0	28.2	28.2
August	30.0	30.0	29.4	29.4	29.0	29.0
September	29.6	29.6	29.3	29.4	29.1	29.1
October	27.7	27.7	28.1	28.1	28.2	28.2
November	24.4	24.3	25.6	25.5	26.3	26.3
December	20.5	20.5	22.4	22.4	23.6	23.6
Year	24.9	25.0	24.9	25.0	25.0	25.1

Figure10. Monthly mean of soil temperature recorded at the Observatory between 1971-2000

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