According to the National Centre for Hydro-Meteorological Forecasting, the figures were below the long-term averages of 5.9 storms and tropical depressions over the East Sea and 2.9 making landfall in Vietnam during the period.
El Nino is forecast to remain strong to very strong from September to November with a 100 per cent probability, including a 93 per cent chance of reaching very strong intensity.
El Nino is already in place, with NINO3.4 sea surface temperatures about 1.8 degrees Celsius above normal in mid-August. The chance of a very strong El Nino is forecast to reach 95 per cent in October-December.
Average temperatures are forecast to be 0.5-1.5 degrees Celsius above normal in September and 1-2 degrees higher in October and November, with some areas even warmer.
Widespread heat is expected to persist in September from Thanh Hoa to Hue and along the south-central coast, with more hot days than usual, while cold air activity is forecast to be weaker.
Moderate to heavy rain could affect areas across the country in September and October, according to Nguyen Duc Hoa, deputy head of the centre's Climate Forecasting Division.
By November, heavy rain is expected to ease and concentrate from Ha Tinh to Hue and along the south-central coast, with possible rainfall shortages during the main rainy season.
The rainy season could also end earlier than usual in the Central Highlands and southern Vietnam.
September rainfall in northern and central Vietnam is forecast to be 10-30 per cent below average, while other regions are expected to receive near-normal amounts.
October rainfall is forecast to be 5-20 per cent above average in the north but below normal elsewhere, with deficits of 20-40 per cent from southern Nghe An to Danang and along the south-central coast.
November rainfall is forecast to be 10-30 per cent above average in the north and from Thanh Hoa to Ha Tinh, but 20-40 per cent below normal from Quang Tri to Lam Dong and 5-15 per cent lower in the south.
El Nino is likely to remain strong to very strong from December 2026 to February 2027, with a 93 per cent probability, including a 70 per cent chance of very strong conditions.
Temperatures are forecast to be 0.5-1.5 degrees Celsius above average nationwide and 1.5-2 degrees higher in the Central Highlands and southern Vietnam.
Storm and tropical depression activity over the East Sea and landfall in Vietnam is also expected to remain below average during the December-February period.
Moderate to heavy rain could continue in December from Quang Tri to Quang Ngai, Khanh Hoa and eastern parts of Gia Lai to Lam Dong. Rainfall is expected to decline further across much of the country in January and February 2027.
Cold air activity from December to January is forecast to be weaker than usual, while severe cold spells could arrive later and occur on fewer days than the long-term average.
The Central Highlands and southern Vietnam could experience particularly dry conditions in January and February, potentially affecting water supplies, agriculture and daily life.
Forecasters also warned of thunderstorms, tornadoes, lightning, hail and strong winds nationwide, while tropical systems and the northeast monsoon could bring strong winds and high waves over the East Sea.
The centre advised authorities and residents to follow short-term forecasts and warnings, particularly for extreme heat, heavy rain, flash floods and landslides, and adjust production and reservoir operations as needed.
