The reading at Hanoi’s Lang station was one of six monitoring sites across northern Vietnam that climbed above 40 degrees that day. Vinh Yen in Phu Tho Province topped the country at 40.8, followed by Lang at 40.7, Bac Ninh at 40.5, Hoi Xuan in Thanh Hoa at 40.5, Do Luong in Nghe An at 40.3 and Huong Khe in Ha Tinh at 40.2.
The National Center for Hydro-Meteorological Forecasting said the severe heat will persist across the north through May 27 and across central Vietnam until around May 28.
In the Red River Delta and Phu Tho, highs are expected to range from 38 to 40 degrees, with some sites exceeding 40.
From Thanh Hoa south to Hue, similar readings are forecast, with western mountainous belts potentially the hottest.
Da Nang and the eastern strip of provinces from Quang Ngai down to Lam Dong, home to Da Lat, are forecast to see 36-38 degrees, with isolated spots above 40.
The current episode began May 23 and is the second major heatwave of May 2026. The weather agency says it is more intense and longer-lasting than the May 13-16 event and ranks among the three most severe May heatwaves recorded since 2021.
Forecasters attribute the surge to a hot low-pressure trough centered to the west of Vietnam, combined with foehn winds descending from the Truong Son mountains. The foehn effect strips moisture from the air as it crosses the range, amplifying thermal radiation and pushing dry heat into the coastal plains.
People travel on a street under severe heat in Hanoi at midday on May 25, 2026. Photo by The Bang |
Truong Ba Kien, Deputy Executive Director of the Center for Meteorological and Climate Research at the Institute of Meteorology, Hydrology, Environment and Marine Sciences, said the heat will begin to ease from the late afternoon of May 27 as the western low-pressure trough weakens and the chance of localized thunderstorms rises.
Kien cautioned that the easing intensity will not bring immediate relief. Background temperatures in Hanoi and across northern provinces are expected to hold at 30-31 degrees, and rising humidity after thunderstorms will keep the air heavy, particularly in dense urban areas where concrete and asphalt amplify the heat.
AccuWeather projects Hanoi will swing between 30 and 43 degrees on May 26, easing to 30-41 on May 27 before dropping roughly 1-2 degrees a day to around 26-35 by the weekend. In the mountain resort of Sa Pa, highs are forecast to fall from 28 degrees on May 27 to about 20 by Saturday.
Authorities have warned that the combination of high heat and low humidity is sharply raising the risk of residential fires, urban blazes and wildfires, and have flagged dehydration and heatstroke risks for people working outdoors. The Ministry of Agriculture and Environment has directed provincial and municipal People’s Committees to review high-risk forest areas, prepare firefighting personnel and equipment, and tighten controls on the use of fire near forests, including slash-and-burn agriculture and brush clearing.
Vietnam’s all-time temperature record, 44.2 degrees Celsius, was set in Nghe An Province on May 7, 2023, the country’s hottest day on record. The 2026 season is shaping up as another in a sequence of severe years. The country logged more than 300 record-high readings nationwide in 2024, and forecasters expect peak heat in the north and central regions to run above the multi-year average through June.
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