The Weather of April 2025 - A relatively dry and bright April
30 April 2025
(First issue on 30 April 2025. Next update on 6 May 2025)
(First issue on 30 April 2025. Next update on 6 May 2025)
Under the influence of the northeast monsoon and a broad band of clouds covering southern China, the weather was mainly cloudy and cold with one or two light rain patches on the morning of the first day of the month. The temperatures at the Observatory fell to a minimum of 12.9 degrees that morning, the lowest of the month. With the band of clouds thinning out, there were sunny periods during the day. The weather became fine and dry the next day. With a dry easterly airstream affecting the coast of Guangdong, it remained fine and very dry on the afternoon of 3 April. While it was generally fine at first on 4 April, a band of clouds gradually covered the coast of Guangdong, leading to cloudier weather that afternoon and the following two days. There were occasional showers on 5 April, with around 10 millimetres of rainfall recorded over many places. With the band of clouds thinning out, the weather became mainly fine on 7 April. It was dry and rather warm during the day. Winds were weak over the coast of Guangdong on 8 – 9 April. The weather in Hong Kong was rather warm with a mixture of sunshine and cloudy episodes.
A southerly airstream brought humid weather in the following three days. Locally, there were fog patches on the morning of 11 April, with the visibility in the harbour once falling below 1000 metres. Besides, a trough of low pressure over northern Guangdong developed into a cold front on the morning of 12 April. As the cold front edged closer to the coastal region, local showers increased with a few squally thunderstorms that afternoon. More than 10 millimetres of rainfall were recorded over many places, and rainfall even exceeded 20 millimetres over Tai Po District. The cold front moved across the coastal areas around that evening. Under the influence of the associated intense and dry northeast monsoon, showers eased off with temperatures falling gradually that night. Strong northerly winds also affected many parts of Hong Kong that night and at first the next day, with winds occasionally reaching gale force offshore and on high ground. The intense monsoon also transported sand and dust southwards from Mongolia and brought widespread sandstorms to many inland areas in China. Under the influence of the very dry continental airstream and the sand and dust weather, the weather was very dry with visibility slightly dropping to around 5 – 6 kilometres over parts of the territory on 13 – 15 April. The relative humidity over many places on these three days fell below 40 percent. The relative humidity recorded at the Observatory on 13 April once fell to 21 per cent, the lowest record in April since the establishment of the automatic weather station at the Observatory's Headquarters in 1984. With plenty of sunshine and weaker winds on 15 April, the temperatures at the Observatory soared to a maximum of 33.0 degrees that afternoon, the highest of the month. It also marked the earliest occurrence of very hot weather in a year and the second highest maximum temperature for April on record.
An easterly airstream affected the coast of Guangdong on 16 – 17 April. While the local weather was mainly fine and dry during the day on 16 April, it became mainly cloudy the next day with coastal fog in the morning and at night. The visibility at Waglan Island once fell below 1000 metres. With a humid southerly airstream replacing the easterly airstream that afternoon, the weather was cloudy with a few showers in the following two days. There was coastal fog on 18 – 21 April. The southerly airstream continued to affect the coast of Guangdong and brought hot weather to Hong Kong on 20 – 24 April. The maximum temperature recorded at the Observatory was 30.6 degrees on 20 April, making it one of the warmest day of the Easter Sunday on record.
A trough of low pressure affected inland Guangdong on 24 April and edged closer to the coastal areas in the evening, bringing showers and a few squally thunderstorms that night and the next day. Showers were heavy on the morning of 25 April. More than 30 millimetres of rainfall were recorded over many places, and rainfall even exceeded 50 millimetres over the eastern part of Hong Kong Island, Kwun Tong and Tseung Kwan O. With a fresh to strong easterly airstream setting in that night, the weather was cloudy with a few showers and became cooler in the following two days. There were also fog patches on 27 April. The visibility at Waglan Island once fell below 1000 meteres. Another trough of low pressure over inland Guangdong edged closer to the coastal areas gradually that night. Apart from coastal fog on the morning of 28 April, there were showers and one or two thunderstorms that day with rainfall exceeding 10 millimetres over many places, and around 30 millimetres of rainfall were even recorded over the northern part of the New Territories. Affected by a relatively dry easterly airstream, there were sunny periods on the last two days of the month.
A southerly airstream brought humid weather in the following three days. Locally, there were fog patches on the morning of 11 April, with the visibility in the harbour once falling below 1000 metres. Besides, a trough of low pressure over northern Guangdong developed into a cold front on the morning of 12 April. As the cold front edged closer to the coastal region, local showers increased with a few squally thunderstorms that afternoon. More than 10 millimetres of rainfall were recorded over many places, and rainfall even exceeded 20 millimetres over Tai Po District. The cold front moved across the coastal areas around that evening. Under the influence of the associated intense and dry northeast monsoon, showers eased off with temperatures falling gradually that night. Strong northerly winds also affected many parts of Hong Kong that night and at first the next day, with winds occasionally reaching gale force offshore and on high ground. The intense monsoon also transported sand and dust southwards from Mongolia and brought widespread sandstorms to many inland areas in China. Under the influence of the very dry continental airstream and the sand and dust weather, the weather was very dry with visibility slightly dropping to around 5 – 6 kilometres over parts of the territory on 13 – 15 April. The relative humidity over many places on these three days fell below 40 percent. The relative humidity recorded at the Observatory on 13 April once fell to 21 per cent, the lowest record in April since the establishment of the automatic weather station at the Observatory's Headquarters in 1984. With plenty of sunshine and weaker winds on 15 April, the temperatures at the Observatory soared to a maximum of 33.0 degrees that afternoon, the highest of the month. It also marked the earliest occurrence of very hot weather in a year and the second highest maximum temperature for April on record.
An easterly airstream affected the coast of Guangdong on 16 – 17 April. While the local weather was mainly fine and dry during the day on 16 April, it became mainly cloudy the next day with coastal fog in the morning and at night. The visibility at Waglan Island once fell below 1000 metres. With a humid southerly airstream replacing the easterly airstream that afternoon, the weather was cloudy with a few showers in the following two days. There was coastal fog on 18 – 21 April. The southerly airstream continued to affect the coast of Guangdong and brought hot weather to Hong Kong on 20 – 24 April. The maximum temperature recorded at the Observatory was 30.6 degrees on 20 April, making it one of the warmest day of the Easter Sunday on record.
A trough of low pressure affected inland Guangdong on 24 April and edged closer to the coastal areas in the evening, bringing showers and a few squally thunderstorms that night and the next day. Showers were heavy on the morning of 25 April. More than 30 millimetres of rainfall were recorded over many places, and rainfall even exceeded 50 millimetres over the eastern part of Hong Kong Island, Kwun Tong and Tseung Kwan O. With a fresh to strong easterly airstream setting in that night, the weather was cloudy with a few showers and became cooler in the following two days. There were also fog patches on 27 April. The visibility at Waglan Island once fell below 1000 meteres. Another trough of low pressure over inland Guangdong edged closer to the coastal areas gradually that night. Apart from coastal fog on the morning of 28 April, there were showers and one or two thunderstorms that day with rainfall exceeding 10 millimetres over many places, and around 30 millimetres of rainfall were even recorded over the northern part of the New Territories. Affected by a relatively dry easterly airstream, there were sunny periods on the last two days of the month.