According to the National Centre for Hydro-Meteorological Forecasting, heatwaves on Wednesday affected areas from Nghe An to Danang, parts of the Central Highlands and southern Vietnam, with temperatures ranging from 35 degrees Celsius to 37 degrees Celsius and higher in some areas.
The hottest temperatures included 38 degrees Celsius in Ba To in Quang Ngai and 38.2 degrees Celsius in Son Hoa in Dak Lak.
Forecasters said northern Vietnam would experience widespread heat from May 14 to May 16, with temperatures of 35 degrees Celsius to 37 degrees Celsius and some areas seeing severe heat above 37 degrees Celsius.
Central Vietnam, particularly areas from Thanh Hoa to Danang and eastern parts of Quang Ngai and Dak Lak, is expected to remain the hottest region, with temperatures forecast at 36 degrees Celsius to 38 degrees Celsius and some locations above 38 degrees Celsius.
In southern Vietnam, hot weather is expected to persist, especially in the southeastern region.
Forecasters said the heatwave in northern and southern Vietnam could ease after May 16, while central areas may continue to experience extreme heat until around May 17.
Authorities warned prolonged heat could increase risks of dehydration and heat exhaustion, noting that actual outdoor temperatures may be 2 degrees Celsius to 4 degrees Celsius higher than forecasts, especially in urban areas.