The forecast follows a recent spell of extreme heat across northern and central Vietnam, which raised concerns about the potential impact of the emerging El Niño weather pattern.
Nguyen Van Huong, head of weather forecasting at the National Centre for Hydro-Meteorological Forecasting, said El Niño has not yet had a direct impact on weather conditions in Vietnam.
However, he said temperatures nationwide from now until August are expected to remain 0.5-1 degree Celsius above the long-term average, leading to more frequent and intense heatwaves than in 2025 and compared with historical norms.
According to Huong, June is likely to bring a further two to three widespread heatwaves, with temperatures commonly reaching 37-39 degrees Celsius.
The highest temperatures are expected in mountainous areas west of the north-central region, stretching from Thanh Hoa to Hue, where readings could climb to 41-42 degrees Celsius.
During the recent heatwave, temperatures across northern and central Vietnam generally ranged from 38 to 40 degrees Celsius, with some locations exceeding 40 degrees Celsius.
Several weather stations recorded their highest May temperatures on record, including Uong Bi in Quang Ninh Province and Hiep Hoa in Bac Ninh Province.
Hanoi was among the areas most affected by the heat. The Ha Dong weather station recorded 41.1 degrees Celsius on May 26, the second-highest May temperature on record at the site.
Huong warned that more frequent and intense heatwaves could increase the risk of heatstroke, forest fires, urban fires and localised water shortages.
He also noted that thunderstorms, lightning and strong winds often follow periods of extreme heat due to clashes between hot and cooler air masses.
Authorities have advised residents to take precautions against heat-related health risks, use electricity safely and closely monitor official weather forecasts and warnings.
