Monthly Meteorological Normals for Hong Kong

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
	No. 1 and/or higher	No. 3 and/or higher	No. 8 and/or higher	No. 9 and/or No. 10
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

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

Month	Total (mm)	Duration (hours)	Number of Days with
			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

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

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

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

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)
		Duration (hours)	Percentage of Possible
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

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

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
	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

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

* 1975 - 2004

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

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

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	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