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According to Vietnam's National Center for Hydro-Meteorological Forecasting, the northwestern Pacific recorded 31 storms by early November 2026, a figure broadly in line with the long-term average.
However, storm activity in the East Sea has been considerably lower. Since the beginning of the year, only five storms and three tropical depressions have been recorded in the region.
Of these, just two systems, one storm and one tropical depression, have affected Vietnam's mainland.
The national weather agency attributed the decline primarily to the effects of a strong to very strong El Nino event.
Interactions between the ocean and atmosphere have altered large-scale atmospheric circulation and the distribution of convection, significantly reducing the conditions favorable for tropical cyclone formation over the East Sea.
Historical observations also show that during El Nino years, the number of storms and tropical depressions directly affecting Vietnam generally tends to be below the long-term average.
Strong El Nino suppresses storm activity in the East Sea
The weather agency forecasts that El Nino will remain very strong through the end of 2026 and into early 2027.
The probability of a very strong El Nino has reached 96%, up three percentage points from the forecast issued for the same period a month earlier. The probability of a strong El Nino now stands at just 4%.
With El Nino expected to maintain its high intensity, the number of storms and tropical depressions developing over the East Sea, as well as those making landfall in Vietnam, is likely to remain below the long-term average through the end of the year.
Historical data indicate that the East Sea typically experiences around 2.5 storms and tropical depressions during this period, with approximately 1.1 systems making landfall in Vietnam.
Nevertheless, the weather agency warned that fewer storms do not mean the absence of danger.
Residents should remain alert to the possibility of storms or tropical depressions forming over the East Sea and directly affecting the mainland, particularly central and southern Vietnam, even though the probability is considered low.
Pacific storms repeatedly turn away from land
Climate change and disaster warning expert Dr. Nguyen Ngoc Huy offered further insight into the unusual storm patterns observed this year.
He noted that most storms, including super typhoons, forming over the Pacific between the beginning of 2026 and the end of October tended to change direction near longitudes 130-140 degrees East.
Rather than continuing westward toward land, many curved northeastward into the vast open waters of the Pacific Ocean.
As a result, relatively few storms have made landfall this year.
According to Huy, several factors influence the movement of tropical cyclones, but the most important this year has been the impact of the exceptionally strong El Nino.
"This phenomenon causes the trade winds to tend to reverse direction, blowing from the western Pacific toward the eastern Pacific instead of from east to west as they do during La Nina and neutral conditions," he explained.
Changes in atmospheric pressure systems have also played an important role.
Huy said the subtropical high-pressure system and the continental high-pressure system to the west, covering areas around mainland China, Japan and northern Vietnam, have frequently maintained relatively high pressure levels of around 1,010-1,025 hPa.
These high-pressure systems effectively create an atmospheric barrier to the west, making it more difficult for storms to move toward the mainland.
If this pressure pattern persists, the likelihood of storms entering the East Sea during November will remain low, he said.
Bao Anh
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