The National Center for Hydro-Meteorological Forecasting said the heatwave, the most intense of the season so far, continued across northern and north-central provinces, including the Red River Delta and Hoa Binh Province. 

In Hanoi, temperatures ranged between 37 and 39 degrees Celsius, with some areas exceeding 39.

Combined with the urban heat island effect, conditions on the ground felt significantly hotter.

By 3:00 pm local time, outdoor surface temperatures in Hanoi were measured at over 54 degrees Celsius.

Despite the heat, many workers remained on the streets. 

Khanh, a 60-year-old motorbike taxi driver from north-central Thanh Hoa Province, said he started his shift at 5:00 am and continued working through the sweltering conditions.

"It's unbearable today. I have high blood pressure, and sometimes I can barely breathe," he said. 

"But I have no choice. Rides are fewer now, and if I don't work, I can't cover living expenses."

At Dong Xuan Market, Thuy, 57, was loading sacks of goods under the sun.

"We start at 6:00 am and finish around 6:00 pm, regardless of the weather," he said, wiping sweat from his face. 

"Today is brutal. After lifting each bag, I'm drenched. I have to drink water constantly just to stay standing."

Health experts have warned that prolonged exposure to extreme heat increases the risk of heatstroke, sunstroke, and cardiovascular complications, especially among vulnerable groups such as the elderly, young children, pregnant women, and those with chronic illnesses.

People working outdoors — including farmers, construction workers, and factory laborers — are advised to avoid direct sun exposure between 10:00 am and 4:00 pm, when UV radiation is at its peak.

Doctors recommend drinking water regularly in small amounts, wearing protective clothing, wide-brimmed hats, and sunglasses, and taking breaks in shaded or ventilated areas every 45 minutes to one hour.