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    The Weather of June 2025 - A hot and relatively dry June

    3 July 2025

    The weather of June 2025 was hotter and drier than usual in Hong Kong, mainly attributing to the stronger subtropical ridge covering southeastern China. The monthly mean minimum temperature of 27.1 degrees was 0.6 degrees above the normal and one of the fifth highest on record for June. The monthly mean maximum temperature of 31.5 degrees and monthly mean temperature of 28.9 degrees were 0.8 degrees and 0.6 degrees above their corresponding normals and both were one of the seventh on record for June. The total rainfall in the month was 237.3 millimetres, about 48 percent of the normal of 491.5 millimetres. With all six months drier than usual, the accumulated rainfall recorded in the first half of the year was only 444.4 millimetres, about 41 percent of the normal of 1082.5 millimetres for the same period and the fifth lowest on record for the same period. 

    With the easterly airstream prevailing over the coast of Guangdong replaced by a southerly airstream, it was hot with sunny periods and there were one or two showers in Hong Kong on the first two days of the month. When a trough of low pressure moved across the coast of Guangdong on 3 June, the local weather turned mainly cloudy with a few showers. An upper-air disturbance and a surface trough of low pressure brought showers to the northern part of the South China Sea and its coastal areas the next day. Locally, it was cloudy with showers. There were thunderstorms in the afternoon. More than 20 millimetres of rainfall were recorded over Lantau Island and the western part of the New Territories. While it was still mainly cloudy with one or two showers on 5 June, it became hot with sunny periods the next day, as the anticyclone aloft covering the coast of southeastern China strengthened gradually. Under the dominance of the anticyclone aloft, the local weather was generally fine with prolonged heat on 7 – 10 June. It was extremely hot on 10 June with the maximum temperature at the Observatory soaring to 35.6 degrees, levelling the record maximum for June since records began in 1884. The maximum temperature at Lau Fau Shan even reached 38.9 degrees, the highest record so far since the setup of the station in 1985. 

    Wutip formed as a tropical depression over the central part of the South China Sea on the night of 10 June. It tracked generally west-northwestward towards Hainan Island and intensified gradually. Its outer rainbands occasionally brought squally showers to the northern part of the South China Sea and the coast of Guangdong. The Observatory issued the first tropical cyclone warning signal of the year on 11 June. Locally, the weather deteriorated gradually with a few squally showers that day. While there were sunny intervals during the day, there were also isolated thunderstorms in the afternoon. Wutip further intensified into a severe tropical storm on 12 June and gradually turned to a north-northeasterly track over Beibu Wan, skirting the western coast of Hainan Island and Leizhou Peninsula in the following two days. Under the influence of Wutip’s outer rainbands, there were squally showers locally on 12 – 14 June, with thunderstorms on 12 – 13 June. The showers were heavy with more than 30 millimetres of rainfall recorded over most parts of the territory on 13 June. The strong winds associated with Wutip affected the Pearl River Estuary and its vicinity on 15 June. Local winds were generally strong, occasionally reaching gale force on high ground. Winds moderated progressively later in the afternoon. While moving northeastwards further into inland areas, Wutip weakened gradually and finally degenerated into an area of low pressure on the evening of 15 June. Locally, there were still a few squally showers that day.

    Under the influence of an active southwesterly airstream, showers and thunderstorms affected Hong Kong on 16 – 17 June. The showers were heavy with squally thunderstorms on 17 June. More than 30 millimetres of rainfall were generally recorded over the territory, and rainfall even exceeded 70 millimetres in the northern part of the New Territories, Tsuen Wan and Sai Kung Districts. With a southerly airstream affecting the coast of Guangdong, it was hot with sunny intervals in the following five days. Meanwhile, there were also occasional showers, with isolated thunderstorms on 19 – 20 June. More than 20 millimetres of rainfall were recorded over the eastern part of the New Territories on 20 June, and the eastern parts of Hong Kong Island and the New Territories on 21 June. While the southerly airstream continued to bring showers and isolated thunderstorms at first on 23 June, with an anticyclone aloft covering southern China, the weather became generally fine and very hot that afternoon, and remained so in the following two days. Besides, an area of low pressure over the central and northern parts of the South China Sea intensified into a tropical depression on 25 June and moved northwestward towards the eastern part of Hainan Island and Leizhou Peninsula. Its outer rainbands brought heavy showers and squally thunderstorms to Hong Kong the next day. Around 30 millimetres of rainfall were generally recorded over the territory, and rainfall even exceeded 50 millimetres over Hong Kong Island and Kowloon. A broad trough of low pressure and an upper-air disturbance affected the coast of Guangdong and brought showers and thunderstorms over the territory on 27 – 28 June.  The showers were heavy in the small hours of 28 June, around 30 millimetres of rainfall were recorded over many places, and rainfall even exceeded 50 millimetres over Tai Po. With the broad trough of low pressure lingering over the coast of Guangdong, the weather remained mainly cloudy with occasionally heavy showers and thunderstorms on the last two days of the month. Around 20 millimetres of rainfall were recorded over Kowloon East and Sha Tin on 29 June. More than 30 millimetres of rainfall were recorded over most parts of the territory, and rainfall even exceeded 50 millimetres in Kowloon East and the eastern part of the New Territories on 30 June.

    Three tropical cyclones occurred over the South China Sea and the western North Pacific in June 2025

    Details of issuance and cancellation of various warnings/signals in the month are summarised 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 2025

    Table 1.1   Tropical Cyclone Warning Signals
    Name of
    Tropical Cyclone
    Signal
    Number
    Beginning Time Ending Time
    Day/Month HKT Day/Month HKT
    WUTIP 1 11 / 6 0040 14 / 6 1220
    3 14 / 6 1220 15 / 6 1540
    no name 1 25 / 6 1420 26 / 6 1420


    Table 1.2   Strong Monsoon Signal
    Beginning Time Ending Time
    Day/Month HKT Day/Month HKT
    15 / 6 1541 15 / 6 2100


    Table 1.3   Rainstorm Warning Signals
    Colour Beginning Time Ending Time
    Day/Month HKT Day/Month HKT
    Amber 17 / 6 0730 17 / 6 1020
    Amber 26 / 6 1705 26 / 6 1905
    Amber 28 / 6 0055 28 / 6 0155
    Amber 30 / 6 2355 1 / 7 0110


    Table 1.4   Thunderstorm Warning
    Beginning Time Ending Time
    Day/Month HKT Day/Month HKT
    3 / 6 0725 3 / 6 0930
    4 / 6 1543 4 / 6 2030
    11 / 6 0225 11 / 6 0345
    11 / 6 1225 11 / 6 1730
    12 / 6 0020 12 / 6 0330
    12 / 6 1940 13 / 6 0535
    13 / 6 0742 13 / 6 1030
    13 / 6 1110 13 / 6 1230
    13 / 6 1415 13 / 6 1630
    13 / 6 1855 14 / 6 0700
    14 / 6 1115 14 / 6 1600
    15 / 6 0845 15 / 6 1100
    15 / 6 1313 15 / 6 1530
    16 / 6 0902 16 / 6 1000
    16 / 6 1440 16 / 6 1615
    16 / 6 1800 16 / 6 2230
    17 / 6 0230 17 / 6 1130
    17 / 6 1742 17 / 6 2330
    19 / 6 0914 19 / 6 1015
    20 / 6 1250 20 / 6 1400
    20 / 6 1636 20 / 6 1730
    21 / 6 0211 21 / 6 0500
    21 / 6 1630 21 / 6 1800
    22 / 6 1442 22 / 6 1600
    23 / 6 0427 23 / 6 0600
    26 / 6 0612 26 / 6 1200
    26 / 6 1630 26 / 6 2130
    27 / 6 0025 27 / 6 0700
    27 / 6 1155 27 / 6 1430
    27 / 6 1536 27 / 6 1830
    27 / 6 2320 28 / 6 0330
    28 / 6 0706 28 / 6 0930
    28 / 6 1749 29 / 6 0100
    29 / 6 0645 29 / 6 1200
    30 / 6 0440 30 / 6 1340
    30 / 6 2045 1 / 7 0400


    Table 1.5   Very Hot Weather Warning
    Beginning Time Ending Time
    Day/Month HKT Day/Month HKT
    7 / 6 1215 11 / 6 1400
    22 / 6 0645 25 / 6 1900


    Table 2   Figures and Departures from Normal - June 2025
    Meteorological Element Figure of the Month Departure from Normal*
    Mean Daily Maximum Air Temperature 31.5 degrees C 0.8 degrees above normal
    Mean Air Temperature 28.9 degrees C 0.6 degrees above normal
    Mean Daily Minimum Air Temperature 27.1 degrees C 0.6 degrees above normal
    Mean Dew Point Temperature 25.1 degrees C 0.2 degrees above normal
    Mean Relative Humidity 80 % 2 % below normal
    Mean Cloud Amount 83 % 6 % above normal
    Total Rainfall 237.3 mm 254.2 mm below normal
    Number of hours of Reduced VisibilityΔ 0 hour 12.7 hours below normal§
    Total Bright Sunshine Duration 144.9 hours 0.6 hour above normal
    Mean Daily Global Solar Radiation 16.62 Megajoule / square metre 2.01 Megajoule above normal
    Total Evaporation 91.7 mm 22.1 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 1991 - 2020 climatological normal, except for number of hours of reduced visibility

      §   Departure from mean value between 1997 and 2024

    daily values of selected meteorological elements for HK for June 2025
    The percentile map of mean temperature of June 2025

      Remarks : Extremely high: above 95th percentile
    Above normal: between 75th and 95th percentile
    Normal: between 25th and 75th percentile
    Below normal: between 5th and 25th percentile
    Extremely low: below 5th percentile
    Percentile and 5-day running average values are
    computed based on the data from 1991 to 2020

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