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Rare phenomenon on the coast of São Paulo draws attention with an extensive tubular cloud during the advance of a cold front, surprises bathers and causes early departure of tourists from the beach in Bertioga throughout the afternoon.
A low, extensive, and tubular-looking formation surprised residents and tourists in the early afternoon of Saturday, May 2, 2026, on Riviera de São Lourenço beach, in Bertioga, on the coast of São Paulo, during the arrival of an already predicted cold front.
As the system advanced along the coast of São Paulo, the phenomenon drew attention due to its size and unusual shape, causing apprehension among bathers who witnessed the rapid change in sky conditions along the sandy strip.
Images recorded by beachgoers and shared on local profiles show the cloud advancing horizontally over the sea and the shoreline, creating a striking contrast with the previously sunny and stable environment.
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Given the sudden change in scenery, some tourists decided to leave the area upon noticing signs of a possible storm, such as the darkening sky, increased winds, and the rapid advance of the formation towards the continent.
Roll cloud impresses tourists in Riviera de São Lourenço
Described as a roll cloud, also called volutus, the formation stands out for its cylindrical and elongated appearance, being considered a rare type of low-altitude cloud that moves horizontally in a well-defined manner.
This type of cloud usually appears in isolation, with an appearance similar to a long tube slowly rotating over the horizon, which increases the visual impact, especially in open areas such as beaches and coastal regions.
In Riviera de São Lourenço, the contrast between the darkened sky, the rough sea, and the sandy strip contributed to amplifying the sense of the phenomenon’s grandeur among residents and visitors who watched the formation advance.
Despite the scare caused by its unusual appearance, the presence of the cloud is directly linked to rapid changes in atmospheric conditions, especially during the action of instability systems associated with the arrival of cold fronts.
According to the Civil Defense of São Paulo, winds linked to the passage of storms on the coast caused gusts that reached 60 km/h, reinforcing the scenario of instability observed along the coast of São Paulo during that period.
Throughout the day, the system progressively advanced along the state’s coast and reached areas near the border with Rio de Janeiro, maintaining unstable weather conditions and rapid variations in wind behavior.
How the roll cloud forms and why it is rare
The formation of a roll cloud occurs when air masses with different temperatures, humidity levels, and densities interact intensely, creating an environment conducive to organized and visibly structured atmospheric movements.
In this process, colder, denser air advances near the surface and forces warm, humid air to rise, generating a movement that can result in horizontal rotation and give rise to the cloud’s characteristic shape.
This dynamic behavior of the atmosphere favors the rolled appearance of the formation, which remains separate from the main base of the storm, a characteristic that differentiates it from other clouds associated with intense rain events.
Meteorologists relate episodes of this type to the approach of cold fronts, especially when there are significant variations in wind speed and direction in different layers of the atmosphere.
Although it can occur in different regions of the world, the roll cloud is considered relatively rare, as it depends on a specific combination of meteorological factors to form and remain visible for long stretches of the sky.
Cold front causes rapid weather change on SP coast
The arrival of the cold front on the coast of São Paulo created ideal conditions for the formation observed in Bertioga, with rapid changes in wind behavior and cloud configuration throughout the day.
In similar situations, it is common for temperatures to drop, cloudiness to increase, and rain to occur shortly after these formations pass, which reinforces the public’s perception of instability.
Despite its imposing and sometimes frightening appearance, the roll cloud should not be confused with tornadoes, as it does not exhibit the same type of vertical circulation associated with more severe phenomena.
Even so, the risks are linked to the surrounding meteorological conditions, including more intense wind gusts, the possibility of heavy rain, and changes in sea conditions in coastal areas.
In Brazil, this type of formation is occasionally observed in coastal regions and during the passage of more intense cold fronts in the South and Southeast regions, where there is a greater contrast between air masses.
Its occurrence depends on a specific combination of wind, humidity, and atmospheric instability, which makes each episode relatively unique in terms of formation and duration.
Videos of the phenomenon go viral and show the cloud’s advance
After the phenomenon was recorded, videos began circulating on social media showing the cloud crossing the sky over Riviera de São Lourenço, which helped to broaden the episode’s repercussion in different regions of the country.
One of the published records was made by the local portal Aconteceu em Riviera, which showed the dimension of the formation advancing over the beach and reinforced the visual impact caused by the cloud among beachgoers.
The scene drew attention mainly due to the uniform advance of the formation, which occupied a large part of the horizon in a few minutes and significantly altered the landscape observed by those present.
For the bathers present, the sudden change in the sky indicated the arrival of instability, leading many to gather their belongings and leave the sandy beach as a precautionary measure given the scenario.
Experts emphasize that, despite its unusual appearance, the roll cloud is part of the natural dynamics of the atmosphere and is associated with situations of contrast between moving air masses.
In such cases, the guidance is to seek safe shelter and follow official communications from the Civil Defense, especially when there is a forecast of severe weather or adverse meteorological conditions in the region.
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