At least five people have died and several more are missing in a series of flooding and landslide events in south and central Vietnam, after several days of continuous heavy rain associated with the southwest (summer) monsoon, which has affected Lam Dong, Bình Thuận, Bà Rịa–Vũng Tàu, Bạc Liêu, Cà Mau, An Giang, Hậu Giang, and Kiên Giang provinces. On Saturday 29 July 2023, a 47-year-old woman was swept away by flood waters in Bình Thuận Province, and was later found dead. On the same day a fishing boat off the same province's coast capsized in high winds, with one of the four crew, a 41-year-old man, missing since the event. A house collapsed amid high winds and heavy rain in Bạc Liêu Province, killing 36-year-old Dang Kim Men, and injuring her 37-year-old husband, Dang Van Dung and their eight-year-old son. A total of 59 nine houses are reported to have been destroyed in the province, and a further 52 to have lost their rooves. Three traffic police officers have been confirmed dead after a landslide hit the station at which they were based at in the Bảo Lộc Pass in Lam Dong Province, at about 2.30 pm local time on Sunday 30 July; a member of the public is still missing following the incident.
Monsoons are tropical sea breezes triggered by heating of the land during the warmer part of the year (summer). Both the land and sea are warmed by the Sun, but the land has a lower ability to absorb heat, radiating it back so that the air above landmasses becomes significantly warmer than that over the sea, causing the air above the land to rise and drawing in water from over the sea; since this has also been warmed it carries a high evaporated water content, and brings with it heavy rainfall. In the tropical dry season, the situation is reversed, as the air over the land cools more rapidly with the seasons, leading to warmer air over the sea, and thus breezes moving from the shore to the sea (where air is rising more rapidly) and a drying of the climate.
Much of Southeast Asia has two distinct Monsoon Seasons, with a Northeast Monsoon driven by winds from the South China Sea that lasts from November to February and a Southwest Monsoon driven by winds from the southern Indian Ocean from March to October. Such a double Monsoon Season is common close to the equator, where the Sun is highest overhead around the equinoxes and lowest on the horizons around the solstices, making the solstices the coolest part of the year and the equinoxes the hottest.
This years rains have been unusually heavy across Southeast Asia, despite there being an El Niño system over the South Pacific, which would usually bring drier conditions. This is probably linked to the rising global temperature, with the record for the Earth's highest average temperature over a 24 hour period being broken three times in July, which has led to higher rates of evaporation from all oceans, leading to unusually high rainfall in many parts of the world.
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