Although none of the three storms and tropical depressions that formed over the East Sea, known internationally as the South China Sea, made direct landfall in Vietnam, their associated weather systems triggered several severe rain spells and thunderstorms across the country.
Historic rainfall
Northern Vietnam endured two widespread rain events. Between Aug. 19 and 24, rainfall generally ranged from 130 to 330 mm, with isolated areas receiving over 500 mm.
Central Vietnam experienced four distinct rain spells. The region from Thanh Hoa Province to Hue City was hit particularly hard between Aug. 19-21 and 24-25, recording 100 to 200 mm of rain, with some localized totals surpassing 250 mm.
According to the National Center for Hydro-Meteorological Forecasting, historic monthly rainfall records were shattered at 13 stations. Bai Chay in Quang Ninh Province in the north recorded an astonishing 992.1 mm, breaking its 1972 record of 894.2 mm. Mau Son in nearby Lang Son Province received 939 mm, surpassing its 2018 record of 782.4 mm.
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Soliders and police evacuate people amid flooding from heavy rains in Lang Son Province, northern Vietnam, Aug. 23, 2026. Photo by Lang Son police |
Other notable monthly totals included Dinh Lap in Lang Son (878.4 mm), Khe Sanh in Quang Tri (757.8 mm), and Thanh Hoa (728 mm).
Five stations also recorded their highest daily rainfall in history. On Aug. 20, Vinh in Nghe An recorded 362.9 mm, breaking a 2010 record, while Huong Son in Ha Tinh recorded 267.6 mm, shattering its 2007 benchmark. Two days later, Mau Son received 359.7 mm in a single day, breaking its 2018 daily record.
Scorching heatwaves
Despite the heavy precipitation, northern and central Vietnam sweltered through several intense hot spells during August. Maximum temperatures frequently reached 35 to 38 C, with some areas exceeding 39 C.
Cam Ranh in Khanh Hoa in central Vietnam hit a blistering 40.4 C on Aug. 27, breaking its previous August record of 39 C. Bac Me in Tuyen Quang in the north reached 40 C on Aug. 13, surpassing a 2021 record.
Average monthly temperatures were also unusually high. Thirty-two stations matched or exceeded Aug. records, including Cam Ranh at 31.7 C, Da Nang at 31.6 C, and Quang Ngai and Hoai Nhon at 31.3 C.
Nationwide, the average August temperature sat 0.5 to 1 C above the long-term average, with the south-central coast and southern Vietnam trending 1 to 2 C higher than normal.
September outlook: Heat and mixed rainfall
The national weather forecast agency expects September temperatures to remain 0.5 to 1 C above the long-term average nationwide. While the intense heat in central Vietnam should gradually ease, the south-central coast may still face heatwaves.
Precipitation patterns will be mixed. Rainfall in northern Vietnam and the area from Thanh Hoa to Ha Tinh is forecast to fall 20 to 40% below the long-term average, while southern Vietnam faces a 5 to 15% deficit. Conversely, the Central Highlands could see 10 to 20% more rain than usual, with the rest of the country experiencing near-normal levels.
Despite the lower overall rainfall forecasts in the north and north-central regions, the agency warned that moderate to heavy downpours remain a significant threat. The Central Highlands and southern Vietnam should prepare for frequent afternoon and nighttime showers and thunderstorms.
Storm activity over the East Sea is expected to track near the long-term average. Historically, September sees about 2.4 storms or tropical depressions form in the region, with 1.2 making landfall in Vietnam.
Authorities caution that the intertropical convergence zone, upper-level convergence, and the southwest monsoon could still trigger widespread rain, thunderstorms, tornadoes, lightning, and hail. Vessels operating at sea are strongly advised to remain on high alert for strong winds and severe weather.