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The Weather of June 2005

    The recurrence of an active trough of low pressure near the south China coast made June 2005 a very wet month. The monthly rainfall of 893.9 millimetres, more than double of the normal figure of 376 millimetres, ranked the fourth highest for the month since record began in 1884. The accumulated rainfall since 1 January amounted to 1512.5 millimetres, 52 percent more than the normal of 992.5 millimetres for the same period. Dominated by rainy and cloudy weather, the total bright sunshine duration in the month was only 82.5 hours, the lowest on record for June.

    Under the influence of the southwest monsoon, it was hot with isolated showers on the first two days of the month. The maximum temperature rose to 33.4 degrees on 3 June, the highest so far this year. The weather deteriorated that evening when thunderstorms associated with a trough of low pressure over south China drifted in from the north to affect Hong Kong. Thundery showers continued to affect the territory in the next two days.

    While it was mainly cloudy with isolated showers from 6 to 9 June, the weather turned sunny and hot on 10 and 11 June. The mainly fine weather during the day on 12 June gave way to showery weather that evening when a trough of low pressure edged close to Hong Kong. Heavy showers and thunderstorms affected the territory in the ensuing five days. The heavy downpour on 15 June brought over 100 millimetres of rainfall to the urban areas and the western part of the New Territories.

    With the trough of low pressure shifting northwards, the weather improved and there were sunny intervals from 18 to 20 June. The trough of low pressure started to move towards the coast again on 21 June, bringing heavy rain and thunderstorms to Hong Kong for four days in a role. On the morning of June 24, torrential rain brought over 200 millimetres of rainfall to Kowloon and the western part of the Hong Kong Island. The Red Rainstorm Warning was issued for the first time this year. There were 28 reports of landslip and over 150 reports of flooding. Flooding was most serious in Tai Po, Sai Wan and Sheung Wan.

    With the dissipation of the trough of low pressure, brighter weather returned the next day. Apart from isolated showers, it was mainly fine and hot from 25 to 28 June. Under the influence of a trough of low pressure over the northern part of the south China sea, the weather turned cloudy with some heavy showers on 29 and 30 June.

    Only one tropical cyclone occurred in the western North Pacific in the month. 

    Details of issuance and cancellation of various warnings/signals in the month are summarized in Tables 1.1 to 1.5.  Monthly meteorological figures and departures from normal for June are tabulated in Table 2.


 

Warnings and Signals issued in June 2005


Table 1.1   Strong Monsoon Signal

Beginning Time Ending Time
Day/Month HKT Day/Month HKT
30 / 6 0830 30 / 6 1030


Table 1.2   Rainstorm Warning Signals

Colour Beginning Time Ending Time
Day/Month HKT Day/Month HKT
Amber 15 / 6 1600 15 / 6 2315
Amber 21 / 6 0910 21 / 6 1440
Amber 24 / 6 0130 24 / 6 1000
Red 24 / 6 1000 24 / 6 1330


Table 1.3   Landslip Warning

Beginning Time Ending Time
Day/Month HKT Day/Month HKT
24 / 6 1015 25 / 6 0745


Table 1.4   Thunderstorm Warning

Beginning Time Ending Time
Day/Month HKT Day/Month HKT
1 / 6 1650 1 / 6 2100
2 / 6 0730 2 / 6 1300
3 / 6 1700 3 / 6 1900
3 / 6 2030 3 / 6 2400
4 / 6 0650 4 / 6 0850
4 / 6 1100 4 / 6 1500
4 / 6 2235 5 / 6 0230
12 / 6 1800 12 / 6 2100
13 / 6 0808 13 / 6 1115
13 / 6 1325 13 / 6 1530
14 / 6 1255 14 / 6 2400
15 / 6 0750 15 / 6 2355
16 / 6 0615 16 / 6 1630
17 / 6 0030 17 / 6 0230
17 / 6 1340 17 / 6 1640
18 / 6 0130 18 / 6 1230
20 / 6 0955 20 / 6 1200
21 / 6 0705 21 / 6 1600
21 / 6 2120 22 / 6 1400
23 / 6 0145 23 / 6 1400
23 / 6 1415 23 / 6 2000
23 / 6 2350 24 / 6 1430
25 / 6 0905 25 / 6 1300
26 / 6 0430 26 / 6 0630
26 / 6 0800 26 / 6 1000
26 / 6 1110 26 / 6 1820
27 / 6 1720 27 / 6 1850
29 / 6 1220 29 / 6 1430
29 / 6 1845 30 / 6 0045
30 / 6 0620 30 / 6 0730
30 / 6 1045 30 / 6 1415
30 / 6 2020 30 / 6 2255


Table 1.5   Special Announcement on Flooding
in the Northern New Territories

Beginning Time Ending Time
Day/Month HKT Day/Month HKT
15 / 6 1107 15 / 6 1310
15 / 6 1515 15 / 6 2315
18 / 6 0335 18 / 6 0708
24 / 6 0620 24 / 6 1300


Table 2   Figures and Departures from Normal - June 2005

Meteorological Element Figure of the Month Departure from Normal*
Mean Daily Maximum Air Temperature 29.7 degrees C 0.6 degree below normal
Mean Air Temperature 27.8 degrees C normal
Mean Daily Minimum Air Temperature 25.9 degrees C normal
Mean Dew Point Temperature 24.9 degrees C 0.5 degree above normal
Mean Relative Humidity 85 % 3 % above normal
Mean Cloud Amount 85 % 10 % above normal
Total Rainfall 893.9 mm 517.9 mm above normal
Number of hours of Reduced VisibilityΔ 9 hours 18.3 hours below normal§
Total Bright Sunshine Duration 82.5 hours 78.6 hours below normal
Mean Daily Global Solar Radiation 10.81 Megajoule / square metre 5.74 Megajoule below normal
Total Evaporation 92.0 mm 51.9 mm below normal


  Remarks : All measurements were made at the Hong Kong Observatory except sunshine, solar radiation and evaporation which were recorded at King's Park Meteorological Station and visibility which was observed at the Hong Kong International Airport.
  Δ

The visibility readings at the Hong Kong International Airport are based on hourly observations by professional meteorological observers in 2004 and before, and average readings over the 10-minute period before the clock hour of the visibility meter near the middle of the south runway from 2005 onwards. The change of the data source in 2005 is an improvement of the visibility assessment using instrumented observations following the international trend.

Before 10 October 2007, the number of hours of reduced visibility at the Hong Kong International Airport in 2005 and thereafter displayed in this web page was based on hourly visibility observations by professional meteorological observers. Since 10 October 2007, the data have been revised using the average visibility readings over the 10-minute period before the clock hour, as recorded by the visibility meter near the middle of the south runway.


  *   Departure from 1961-1990 climatological normal, except for number of hours of reduced visibility.
  §   Departure from mean value between 1997 and 2004.


daily values of selected meteorological elements for HK for June 2005

Extract of Meteorological Observations in Hong Kong for June 2005