Meteorologists are warning that a new cyclone is on track to develop off Brazil’s southern coast in the coming days, bringing a rapid shift from scorching heat to violent storms across parts of the country’s South and Southeast.
Heatwave sets the stage for a new cyclone
Forecasters from Meteored report that a broad area of low pressure will begin organising over southern Brazil between Friday and Saturday, after days of extreme heat across the region.
Before the cyclone takes shape, residents in the South are enduring oppressive conditions. From 26 January to 3 February, temperatures are expected to stay well above average, with many areas topping 30°C by mid-morning.
Meteored projects afternoon highs nearing 40°C and repeatedly surpassing 36°C through Wednesday, especially in Rio Grande do Sul and western parts of the South.
This heat, combined with high humidity, is creating the perfect fuel for severe storms once a stronger weather system arrives. The atmosphere above the region is becoming increasingly unstable, making it easier for thunderstorms to grow quickly and turn dangerous.
When the cyclone is expected to form
According to the current forecast, scattered storms will start to flare up early in the week, then organise into a more robust system by the end of it.
- Monday–Tuesday (27–28 January): isolated storms, mainly in Paraná
- Wednesday (28 January): instability grows, with more widespread showers and storms
- Thursday (29 January): storms expand over much of the South
- Friday–Saturday (30–31 January): new cyclone expected to form off the coast between South and Southeast Brazil
On Thursday, thunderstorms should spread across much of Rio Grande do Sul, Santa Catarina and Paraná. Weather models indicate that storm systems will begin to line up along Brazil’s western border, particularly near Uruguaiana, where intense episodes could start in the morning before shifting eastward.
Between Friday and Saturday, forecasters anticipate the birth of a new cyclone over the Atlantic, off Brazil’s southern coastline, between the South and Southeast regions.
Once formed, this cyclone will likely deepen over the ocean, helping to channel heavy rain, strong winds and rough seas toward the coastal strip.
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States and regions most at risk
The strongest effects are expected across the three southern states: Rio Grande do Sul, Santa Catarina and Paraná. Some areas are already under alert for turbulent weather and heat-related stress.
Key areas under weather alert
| State/region | Main concerns |
|---|---|
| West and Campanha of Rio Grande do Sul | Extreme heat, storms spreading from the border, possible intense downpours |
| Central-west Santa Catarina | Storm development as systems advance eastward |
| Paraná (central and northeast) | Isolated storms early in the week, then heavy rain with totals above 100 mm |
| Eastern parts of the three southern states | Concentrated heavy rain and storms on Friday and Saturday |
By Friday, the focus of heavy rain and storms is expected to shift toward the eastern half of the southern states, including the northeast of Rio Grande do Sul. These coastal and near-coastal zones could see rapid changes in conditions as the cyclone strengthens nearby over the sea.
Rainfall totals and local differences
While the region will face widespread instability, rain will not fall evenly everywhere. Some areas could be soaked, while nearby cities see only short, passing showers.
Meteored’s forecast suggests that, by Saturday, total rainfall across much of the South will sit between 50 mm and 80 mm. For many towns, that is the equivalent of several days’ worth of rain squeezed into a much shorter period.
In central and northeastern Paraná, rainfall totals may exceed 100 mm, increasing the chance of flooding in vulnerable areas.
In contrast, parts of Rio Grande do Sul might see rain arriving in bursts, with long breaks in between storms. This irregular pattern can be misleading: even if skies look clear for several hours, powerful cells can still develop quickly later in the day.
How the cyclone could affect daily life
The combination of lingering heat and approaching storms can affect transport, energy supply, and outdoor work. Roads may flood in low-lying zones, and lightning strikes could disrupt power lines, especially in rural regions.
Residents in the West and Campanha of Rio Grande do Sul, as well as interior areas of Santa Catarina and Paraná, should prepare for rapid shifts from intense heat to strong winds and heavy rain. Farmers, in particular, may face a tricky balance between much-needed moisture and potential damage to crops from hail or strong gusts.
Practical steps for residents
- Secure loose items on balconies, rooftops and gardens before Friday.
- Avoid parking vehicles under large trees or near unstable structures.
- Plan travel with extra time in case of flooded roads or traffic delays.
- Keep mobile devices charged in case of electricity cuts.
- Stay hydrated and limit outdoor work during the hottest hours.
Why heat and cyclones often arrive together
Cyclones in this part of South America are usually linked to strong contrasts in temperature. When very hot, humid air from the interior clashes with cooler, drier air over the Atlantic, the atmosphere tries to balance that difference. A spinning low-pressure system, or cyclone, can form along that boundary.
The current pattern over Brazil fits that script. Prolonged heat over the South is loading the air with moisture and energy. As a cold front approaches from the south or southwest, that energy can be released in the form of towering storm clouds, intense lightning, and rapid wind shifts.
Key weather terms explained
The word “cyclone” in this forecast refers to a mid-latitude low-pressure system, not a tropical cyclone or hurricane. These systems are common in the South Atlantic, though their strength and exact path can vary widely from event to event.
Meteorologists also talk about “instability”. This simply means that air near the surface is warmer and more humid than the air above. When that happens, rising air parcels can accelerate upward, building tall thunderclouds capable of producing hail, strong winds and heavy rain.
A week that begins with oppressive heat and scattered storms is likely to finish with a fully developed cyclone offshore, pushing bands of rain and wind toward Brazil’s southern coastline.
Computer models will continue to refine the details as the system approaches. Small shifts in where the cyclone forms along the coast could change which cities see the worst weather, but the message from meteorologists is already clear: the South of Brazil faces several days of intense heat, followed by a volatile and, at times, dangerous turn in conditions as the new cyclone takes shape.
