The blast of heat that gripped northern and central Vietnam from May 22 to 27 was the second major heatwave of the month and one of the three most intense May episodes since 2021, according to the National Center for Hydro-Meteorological Forecasting. Driven by a hot low-pressure system to the west combined with strong foehn winds spilling off the Truong Son mountains, the heat peaked between May 24 and 26.
At its height, Hanoi, the northern delta, the northern midlands and the central region from Thanh Hoa to Hue registered 38 to 40 degrees Celsius, with isolated spots above 40 C, a level Vietnam's meteorological service classifies as particularly severe.
A string of weather stations broke or matched their May highs. In Quang Ninh, Uong Bi station hit 38 C on May 25, well above the previous May record of 37.5 C set on May 16, 2013. Hiep Hoa station in Bac Ninh Province reached 39.7 C, beating the old May high of 39 C from May 19, 2019. Bac Giang station climbed to 39.4 C, topping the 39.1 C mark from May 21, 2020. Bac Ninh station and Hai Duong station in Hai Phong city tied their May records of 40.5 and 39.6 C, both also set on May 21, 2020.
Hanoi was the epicenter. Daily highs hovered between 39 and 40 C for several days, and on May 26 four of the city's five weather stations cleared 40 C. Lang station hit 41.1 C, the second-highest May reading on record for the capital. Hanoi's all-time May high of 41.3 C was recorded at Ha Dong station in 2019. Lang's own annual record stands at 41.8 C, set on June 4, 2017, the same day Ha Dong logged Hanoi's absolute high of 42.5 C.
