According to the National Center for Hydro-Meteorological Forecasting, northern and central Vietnam experienced two widespread heatwaves in May, from May 13-17 and May 23-28. Maximum temperatures generally ranged between 36°C and 39°C, with some locations exceeding 40°C. By May 29, the heat had eased in most areas, remaining concentrated mainly between Nghe An and Hue and along parts of the south-central coast.

Southern Vietnam also recorded three periods of widespread heat from May 1-3, May 7-17 and May 22-26, with temperatures commonly reaching 35°C to 38°C.

Meteorologists described the late-May event as the most intense heatwave recorded during the same period since 2021. The heat arrived unusually early in the day, beginning around 9am and persisting until 7pm. Overnight temperatures remained above 30-31°C, creating oppressive conditions around the clock.

In Hanoi and Nghe An, temperatures exceeded 41°C at certain monitoring stations.

The weather agency also reported that 19 observation stations recorded new all-time May temperature highs, while another 17 stations registered their second-highest May temperatures on record.

Summer expected to be hotter than normal

Weather experts forecast that widespread heat will continue during the first days of June, with additional heatwaves likely throughout the month across northern and central Vietnam.

Authorities have warned of the possibility of severe and exceptionally severe heat episodes.

Hoang Phuc Lam, Deputy Director of the National Center for Hydro-Meteorological Forecasting, said two to three additional heatwaves are expected in June. Temperatures will generally range from 37°C to 39°C, while some areas could reach 41-42°C, particularly mountainous districts west of Thanh Hoa and Hue.

Meteorologists also expect El Nino conditions to begin developing during June. Between now and August, nationwide temperatures are forecast to remain approximately 0.5°C to 1.5°C above long-term averages.

“This means this summer could be hotter than usual, with more frequent and more intense heatwaves compared with 2025 and long-term climate averages. The likelihood of new all-time temperature records is also increasing,” Lam said.

Nguyen Ngoc Huy, a climate change and disaster risk reduction expert, shared a similar assessment, noting that strengthening El Nino conditions could contribute to widespread heatwaves between June and August.

Tropical storm activity may begin in June

Rainfall patterns are expected to vary across the country during June.

Northern Vietnam, along with Thanh Hoa and Nghe An provinces, is forecast to receive rainfall 5-10% above average. Most other regions are expected to record precipitation levels 10-25% below normal.

Heavy rain events are likely to continue across northern Vietnam, the Central Highlands and southern provinces, while localized showers and thunderstorms remain possible elsewhere.

Meteorologists also noted that tropical storms or tropical depressions may develop over the East Sea this month at levels close to historical averages. On average, June typically sees around 1.1 tropical systems forming over the East Sea and 0.3 making landfall in Vietnam.

The weather agency warned that dangerous weather conditions, including thunderstorms, whirlwinds, lightning, hail and strong winds, could occur nationwide, particularly in northern Vietnam, the Central Highlands and the south.

As climate change continues to make weather patterns more extreme and less predictable, authorities are urging residents and local governments to closely monitor forecasts and warnings, adjust production and travel plans when necessary, and take precautions to protect lives and property.

Bao Anh