Inner Ho Chi Minh City could see 90-100 more days a year above 35 degrees Celsius by the end of the century under a high-emissions scenario, and inner Hanoi 50-90 more, Vietnam's updated climate projections show.
The 2025 edition of the national climate change scenario, published by the Ministry of Agriculture and Environment on Oct. 9, projects that Vietnam's two most populous cities will keep warming through the 21st century, with their urban cores heating faster than the citywide average, more hot days and longer heat waves.
Under the high-emissions scenario, average annual temperatures in Hanoi and HCMC could rise 1.7-2 degrees Celsius by mid-century from the 1995-2014 baseline, said Nguyen Huu Quyen of the Institute of Meteorology, Hydrology, Environment and Marine Sciences.
The increase would be 2.2-2.8 degrees in inner Hanoi and 2.1-2.2 degrees in inner Ho Chi Minh City.
By the end of the century, the citywide average is projected to be 3-3.4 degrees higher in Hanoi and 3-3.1 degrees higher in Ho Chi Minh City. In the urban cores the rise would reach 3.6-4.2 degrees and 3.5-3.7 degrees respectively.
Days with highs above 35 degrees in inner Hanoi could increase by 30-70 by mid-century and by 50-90 by the end of the century under the same scenario, Quyen said. Across Hanoi as a whole, the end-of-century increase would be 25-65 days.
In inner Ho Chi Minh City, such days could increase by 35-70 by mid-century and by 90-100 by the end of the century, compared with 30-50 for the city as a whole.
In the baseline period, Hanoi averaged 35 such days a year and Ho Chi Minh City 70.
A heat wave with highs above 35 degrees could also last 15-22 days longer in inner Hanoi and 20-24 days longer in inner Ho Chi Minh City by the end of the century under the high-emissions scenario.
Truong Ba Kien, deputy director of the institute's meteorological research center, said that under the current climate change scenario Vietnam would no longer have a winter from around the middle to the end of this century.
 |
|
People walk in Hanoi on a hot day in June 2026. Photo by VnExpress/The Bang |
Temperatures in the two cities' urban cores are rising faster than on their outskirts because of the combined effect of global climate change and urban surfaces. Densely built areas with extensive concrete and asphalt and little green space absorb and store more heat.
This is known as the urban heat island effect, in which densely built areas are usually hotter than surrounding areas with more trees and water. The temperature gap is not fixed and varies with the time of day, the season and the weather.
The scenario also warns that days with a high risk of heat stress could increase by 80 in inner Hanoi and 100 in HCMC by the end of the century under the high-emissions scenario. On such days the body is under heavy strain from the combination of heat, humidity, sunshine and wind.
Pham Thi Thanh Nga, the institute's director, said each sector needs to prepare its own response plans, with the health sector readying resources to support people during extreme heat and agriculture adjusting crop varieties and planting seasons.
She said ministries, sectors and localities should use the scenario as the scientific basis for long-term adaptation plans instead of responding only when disasters strike. Policymakers need to factor extreme heat into planning and infrastructure investment and prioritize resources for vulnerable groups.
Vietnam first drew up a climate change scenario in 2009 and is required to update it every five years. Ministries, sectors and localities use it as a basis for their socio-economic development plans.