The rains started to fall Monday and are expected to last until Saturday, according to the Hydro-Meteorological Observatory for the Southern Region.
The amount of rainfall should be measured at 20-50 millimeters per 24 hours, it said. Rainfall of 180 millimeters a day is considered heavy.
The rains have ended a heatwave that had lasted over two weeks in Ho Chi Minh City and southern Vietnam, during which the mercury remained in the 35-36 degrees Celsius from morning throughout the afternoon across the southern metropolis.
The wave is a normal weather phenomenon that usually occurs in June or August in southern Vietnam due to the influence of a subtropical high-pressure area combined with hot low-pressure.
The rainy season has arrived early this year in southern Vietnam, beginning in April instead of late April or even mid-May.
The south of Vietnam only has two seasons, dry and rainy. The rainy season normally lasts until November.