Saigonese suffer longest heat wave in 30 years

By Viet Duc   April 28, 2024 | 03:00 pm PT
Saigonese suffer longest heat wave in 30 years
A worker shields himself from the scorching sun at a construction site in HCMC, April 9, 2024 when the outdoor temperature rises to 41 degrees Celsius. Photo by VnExpress/Quynh Tran
Residents of Ho Chi Minh City are enduring the longest heat wave in nearly 30 years, though temperatures have not yet reached historical highs.

Ever since the end of March, HCMC in specific, and the southern region in general, have endured an indefatigably severe heatwave.

Temperatures have consistently exceeded 35 degrees Celsius - a threshold for heatwaves, according to meteorological classifications.

In reality, the perceived outdoor temperature may be 3-5 degrees higher.

An analysis by VnExpress using daily temperature data over the past 30 years in HCMC and its neighboring provinces of Dong Nai, Binh Duong, and the nearby province of Binh Phuoc, shows that the first four months of this year have experienced a relentless extended heat wave that has broken many historical records.

Since the beginning of the year, HCMC has recorded 74 heat wave days, an annual record for the last nearly 30 years, according to data from the Southern Regional Hydrometeorological Center.

It means that on average, two out of every three days temperatures in the city exceeded 35 degrees Celsius.

The frequency of heat waves is double the city's average over the past three decades.

Over the past four months in particular HCMC residents have endured an intense period of scorching heat.

The number of heatwaves - days with temperatures above 35 degrees Celsius for at least two consecutive days - is similar to previous years with the El Nino weather phenomenon.

However, each period has become longer, with the current ongoing heatwave that started March 29 has lasted 28 days so far, the longest record since 1997. And the sizzling temperatures have not yet shown any signs of subsiding.

Temperatures have been rising since the beginning of the year. The highest 2024 temperature recorded in the city so far was 39 degrees Celsius, nearly reaching the historical threshold of 39.6 degrees Celsius (set in 1998). However, outdoor temperatures are usually perceived to be higher.

Nguyen Ngoc Huy, a meteorological, hydrological, and climate change research expert, said during extended heatwaves, the actual temperature from the fifth or sixth day is often much higher than the number measured in meteorological tents, due to heat accumulation.

This comes from the resonance between the temperature of sunlight and the absorption of heat by materials in the environment, such as concrete surfaces.

"The longer the heatwave lasts, the more stressful and uncomfortable people become, leading to a perception of higher temperatures than the meteorological figures," he said.

In the three provinces of Binh Duong, Binh Phuoc, and Dong Nai, the ongoing dry season (which typically lasts from late November to early May and peaks in April) has also been one of the hottest in three decades.

The monitoring stations in Bien Hoa City, Dong Nai Province and Phuoc Long Town in Binh Phuoc have recorded temperatures exceeding historical records set in 1998, at 40 and 38.3 degrees Celsius, respectively.

In Binh Phuoc, the heatwave has now lasted for 49 days, matching the peak level set in 1998.

Binh Duong and Dong Nai are also experiencing unusually long heatwaves, lasting 50 and 33 days, respectively, and have not yet ended.

Le Dinh Quyet, head of the meteorological forecasting department at the Southern Regional Hydrometeorological Station, said the main reason for the record number of heatwave days in many southern localities is the El Nino phenomenon.

El Nino, characterized by elevated sea surface temperatures in the central and eastern Pacific Ocean, typically induces reduced rainfall in regions across Vietnam, particularly the Central Highlands and southern areas.

This often results in drought conditions, affecting water supplies needed for domestic use, agricultural irrigation, and hydropower generation.

Notably, the 2015-2016 El Nino event, one of the most intense on record, triggered severe droughts across Vietnam.

Moreover, El Nino events typically coincide with above-average temperatures, leading to widespread heat waves across the country.

According to the U.S. National Atmospheric and Oceanic Administration (NOAA), in the last 10 years, 2024 has not yet been the year with the strongest El Nino activity.

However, the number of heat wave days is still at a record high in many Vietnamese localities.

Quyet analyzed that the impact of El Nino does not completely correlate with the intensity of the heatwaves.

"It's not that a stronger El Nino will necessarily lead to longer heatwaves. It can only be said that when there is an El Nino, the temperature will certainly be higher, and there will be less rain, 2024 included," he said.

Besides El Nino, the continuous activity of the hot low-pressure areas to the west have also made the current heatwave in HCMC and other southern provinces more intense, according to Huy.

This low-pressure area operates from India and Bangladesh to Thailand, Laos, Cambodia, then affecting Vietnam, he said.

Head of the meteorological forecasting department of the Southern Hydrometeorological Station, Quyet, said that the heat will last until the end of this month.

In May, the first seasonal rains may appear.

However, he warned that hot weather will continue at the beginning of the rainy season.

The highest temperature during the day usually falls between 1-5 p.m., but could still remain above 35 degrees Celsius. Meanwhile, rain often appears in the evening.

El Nino is forecast to end this year, however, Quyet believes that the intensity of heat in the south is unlikely to decrease in the dry season in the coming years. Current climate fluctuations are becoming increasingly unusual. They easily break old rules, which means forecasting is also more difficult.

"There is only one sure trend, which is that the temperature will keep increasing, both globally and in Vietnam," Quyet said.

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