Northern Vietnam is set to experience a widespread spell of heavy rainfall from the evening of June 15 through June 18, with some areas forecast to receive more than 350mm of rain, according to the National Center for Hydro-Meteorological Forecasting.

The weather system is expected to bring a heightened risk of flash floods, landslides and flooding in low-lying areas, particularly across mountainous and midland provinces.

According to forecaster Pham Thi Cham, thunderstorms had already developed across northern mountainous areas on the afternoon of June 15, bringing showers and localized heavy rain to parts of Thai Nguyen, Cao Bang and Tuyen Quang provinces. Rainfall is expected to intensify significantly from the evening onward.

The conditions are being driven by a low-pressure trough moving southward into northern mountainous regions, combined with upper-level wind convergence extending to an altitude of around 5,000 meters.

Meteorologists forecast widespread moderate to heavy rain across the northern mountains and midlands between June 15 and June 18, with cumulative rainfall generally ranging from 100mm to 200mm and isolated totals exceeding 350mm.

Rain is expected to be concentrated from late afternoon through the following morning, with some locations likely to experience more than 100mm of rainfall within just three hours.

Quang Ninh, Lang Son, Bac Ninh, Cao Bang, Tuyen Quang and Thai Nguyen are forecast to receive between 100mm and 200mm of rainfall, with some locations exceeding 300mm. Lao Cai, Phu Tho, Son La, Dien Bien and Lai Chau are expected to record between 70mm and 150mm, with isolated areas surpassing 250mm.

The provinces facing the highest risk of flash floods and landslides include Lang Son, Cao Bang, Tuyen Quang, Lai Chau and Dien Bien.

"Persistent heavy rainfall will significantly increase the risk of flash floods and landslides on steep slopes," Cham said.

She added that small rivers, streams and upper reaches of major river systems across northern Vietnam could experience rising water levels, with flood peaks increasing by between two and four meters.

During this period, flood levels on smaller rivers could reach Warning Levels 1 and 2, potentially causing inundation in low-lying riverside communities.

Northern heatwave ends as temperatures fall

For Hanoi and the Red River Delta, scattered showers and thunderstorms are forecast from the night of June 15 through June 17, primarily during the evening and nighttime hours. Some locations may receive more than 70mm of rainfall within a 24-hour period.

The rain is expected to bring a sharp drop in temperatures, effectively ending the recent heatwave across northern Vietnam.

Daytime temperatures in the delta are forecast to range between 31 and 33 degrees Celsius, while mountainous and midland areas are expected to see highs of 29 to 31 degrees Celsius, creating more comfortable weather conditions.

Rainfall in northern mountainous areas is expected to ease from June 19, with only scattered showers and thunderstorms remaining. Elsewhere across northern Vietnam, isolated showers are forecast.

From around June 20, however, widespread heat is expected to return to the Red River Delta before expanding to other parts of the region.

Central Vietnam remains under intense heat

In contrast to the cooler conditions in the north, central Vietnam is expected to remain under prolonged heatwave conditions.

On June 15, provinces stretching from Thanh Hoa to the eastern part of Dak Lak continued to experience severe heat, with daytime temperatures ranging from 36 to 38 degrees Celsius and some locations exceeding 39 degrees Celsius.

Temperatures are expected to ease slightly between June 16 and June 19, falling to around 35 to 37 degrees Celsius, although some areas may still exceed 38 degrees Celsius.

Meteorologists warn that severe heat could intensify again from June 20, prompting residents to take precautions against heat-related health risks.

Meanwhile, from now through June 24, the Central Highlands and southern Vietnam are expected to experience regular afternoon and evening showers and thunderstorms under the influence of the southwest monsoon. Some areas may see locally heavy rainfall.

Bao Anh