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The Year's Weather - 1999

    With an annual mean temperature of 23.8 degrees, 1999 was the second warmest year on record. The monthly mean temperatures for all months except May, August and December were above their respective normal figures. In the year, eight tropical cyclones necessitated the hoisting of local Tropical Cyclone Warning Signals as compared to the annual average of about six. Five of this year's tropical cyclones necessitated hoisting of the No. 8 or higher signals and the last time this occurred was in 1964. Four of these tropical cyclones crossed Hong Kong, breaking the previous record of two in 1964. The Hurricane Signal, No. 10 was hoisted in September for Typhoon York and it was the first time since 1983 that this signal was hoisted. The annual rainfall amount of 2129.1 millimetres was close to normal.

    January 1999 was warmer than normal with below average rainfall.

    Sunny and dry weather dominated February. The mean temperature of 18.7 degrees was the third highest for the month and the Fire Danger Warning was in force on a total of 22 days.

    Warm and relatively dry weather continued into March. The accumulated rainfall of only 28.1 millimetres was recorded in the first quarter of the year against a normal of 138.3 millimetres for the same period.

    April was very warm again with slightly above average rainfall. The first Tropical Cyclone Warning Signal was hoisted due to Typhoon Leo and the hoisting of the Strong Wind Signal No. 3 on 30 April was an early record.

    It was cooler and drier than usual in May. The approach of Typhoon Leo necessitated hoisting of the No. 8 Northeast Gale or Storm Signal in Hong Kong on 2 May. This was the earliest hoisting of a No. 8 signal in any year.

    With a monthly mean temperature of 28.9 degrees, June 1999 was the warmest June on record. The Increasing Gale or Storm Signal No. 9 was hoisted on 7 June as Typhoon Maggie swept across Hong Kong in the early hours.

    July was warmer and cloudier than normal with a tropical cyclone affecting Hong Kong during the month.

    Typhoon Sam traversed the northeastern part of the New Territories in the evening of 22 August and necessitated the hoisting of the Gale or Storm Signal No. 8. Sam brought torrential rain to the region making it the wettest tropical cyclone to affect Hong Kong on record. Black Rainstorm Warning Signals were issued on 23 and 24 August.

    September was again wetter than normal with three tropical cyclones affecting Hong Kong during the month. The Hurricane Signal, No. 10 was hoisted on 16 September during the passage of Typhoon York. Severe Tropical Storm Cam traversed Hong Kong on 26 September and necessitated the No. 8 signal.

    October was warmer and drier than normal. Typhoon Dan became the last tropical cyclone that necessitated hoisting of local warning signals in the year.

    November was again warmer and drier than normal.

    The mean temperature of December was below normal. An intense surge of the winter monsoon brought cold and dry weather to Hong Kong on 19 December and the Cold Weather Warning was issued by the Observatory for the first time. Temperatures dropped to the year's minimum of 5.8 degrees on 23 December. Formation of ice and thin frost were reported on high grounds and in the northern part of the New Territories.

Summary of Meteorological Observations in Hong Kong, 1999
 
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Month		 blank space
Mean
Pressure
(hPa)		 Air     Temperature blank space
Mean
Dew Point
Temperature
(deg. C)		 blank space
Mean
Relative
Humidity
(%)		 blank space
Mean
Amount
of Cloud
(%)		 blank space
Total
Rainfall
(mm)
blank space
Mean Daily
Maximum
(deg. C)		 blank space
Mean
(deg. C)		 blank space
Mean Daily
Minimum
(deg. C)
January 1018.3 19.6 17.3 15.5 11.6 70 60 4.5
February 1020.2 21.2 18.7 16.5 12.0 67 40 Trace
March 1011.5 22.7 20.4 18.4 17.5 84 76 23.6
April 1011.3 26.9 24.3 22.4 20.2 79 75 176.9
May 1009.7 27.2 24.9 23.1 21.5 82 83 177.8
June 1005.5 31.5 28.9 26.8 24.7 79 74 197.4
July 1003.0 31.6 29.2 27.2 25.4 81 82 203.8
August 1005.0 30.8 28.3 26.2 24.9 82 80 892.0
September 1006.7 30.4 27.8 25.9 23.5 78 70 365.7
October 1013.7 28.6 26.2 24.6 20.9 73 62 38.8
November 1017.1 24.5 22.2 20.3 16.2 70 53 15.7
December 1021.3 19.1 16.8 14.8 8.4 60 51 32.9
Mean/Total 1011.9 26.2 23.8 21.8 18.9 75 67 2129.1
Normal 1012.9 25.7 23.0 20.9 18.6 77 65 2214.3
Station Hong  Kong  Observatory


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Month		 blank space
Total Bright
Sunshine
(hours)		 blank space
Mean Daily
Global Solar
Radiation
(MJ/m2)		 blank space
Total
Evaporation
(mm)		 blank space
Prevailing
Wind
Direction
(degrees)		 blank space
Mean
Wind Speed
(km/h)
January 133.3 10.14 73.4 060 24.9
February 182.6 13.33 94.9 070 24.9
March 99.4 9.35 64.5 070 25.1
April 139.7 14.03 114.9 070 27.2
May 109.8 13.36 97.6 070 25.1
June 191.0 16.38 136.8 190 20.0
July 158.0 15.30 130.6 220 20.9
August 138.5 12.56 135.2 220 19.7
September 148.5 13.39 123.0 010 21.7
October 195.2 14.51 130.6 080 28.3
November 191.2 13.03 105.5 070 29.1
December 165.4 10.80 86.3 010 28.0
Mean/Total 1852.6 13.02 1293.3 070 24.6
Normal 1948.1 14.46 1528.8 080 22.6
Station King's  Park Waglan  Island^


The minimum pressure recorded at the Hong Kong Observatory was 976.1 hectopascals at 0809 HKT on 16 September.
The maximum air temperature recorded at the Hong Kong Observatory was 35.1 degrees Celsius at 1450 HKT on 21 August.
The minimum air temperature recorded at the Hong Kong Observatory was 5.8 degrees Celsius at 0551 HKT on 23 December.
The maximum gust peak speed recorded at Waglan Island was 234 kilometres per hour from 020 degrees at 0514 HKT on 16 September.
The maximum instantaneous rate of rainfall recorded at King's Park was 180 millimetres per hour at 0504 HKT on 16 September.

Trace indicates rainfall amount less than 0.05 mm

^ In case the data are not available from Waglan Island, observations of Cheung Chau or other nearby weather stations will be incorporated in computing the Prevailing Wind Direction and Mean Wind Speed