Forecasters are tracking a new cyclone expected to form off Brazil’s southern coast in the coming days, bringing a sharp break from extreme heat and triggering widespread storms across the South and parts of the Southeast. While not every city will be hit in the same way, the system could bring intense rain, powerful gusts, and dangerous lightning to millions of people.
Heat first, storms next: what the forecast shows
Meteorologists at Meteored warn that the atmosphere over southern Brazil is entering a volatile phase between 26 January and 3 February. For several days, heat and humidity will build across the states of Rio Grande do Sul, Santa Catarina and Paraná, feeding the energy needed for severe storms and, eventually, a coastal cyclone.
Until Wednesday 28 January, maximum temperatures in parts of southern Brazil are expected to approach 40°C, with many areas exceeding 36°C every afternoon.
Forecasters say that the “feels-like” temperature will be especially oppressive from early morning, as thermometers in Rio Grande do Sul push past 30°C before midday. This stifling mix of heat and moisture increases the chance of intense downpours when storms do form.
Key dates for the new cyclone
While the heat is already being felt, the dramatic weather shifts unfold in stages:
- Monday–Wednesday (26–28 Jan): Persistent heat, with scattered, isolated storms, especially in Paraná on Tuesday.
- Thursday (29 Jan): Thunderstorms expand across much of the South, starting near the western border.
- Friday (30 Jan): Heavy rain and storms focus on the eastern halves of the southern states and parts of northeastern Rio Grande do Sul.
- Friday–Saturday (30–31 Jan): The new cyclone is expected to take shape off the Brazilian coast, between the South and Southeast regions.
This timeline can still shift slightly, but the window for cyclone formation is currently pinned between Friday and Saturday.
Which regions are on alert
The first warning signs come from the western part of the South, where intense heat and growing instability will collide.
Western and “Campanha” areas of Rio Grande do Sul, along with central-western Santa Catarina and Paraná, are on special alert for powerful storms.
On Thursday 29 January, storm clusters are expected to emerge along the western border, near cities such as Uruguaiana. These storms may rapidly intensify, bringing strong wind gusts, hail in some spots, and frequent lightning.
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From there, the unstable weather is forecast to push eastwards, affecting more densely populated areas of Santa Catarina and Paraná. By Friday, the focus shifts to the eastern halves of these states, including coastal and near‑coastal zones, with a higher chance of heavy showers and thunderstorms.
Rainfall projections and uneven totals
One of the quirks of this system is how uneven the rain will be. While some towns face intense downpours, others just a few kilometres away may receive far less.
| Region | Expected rainfall (up to Saturday) | Risk level |
|---|---|---|
| Most of Rio Grande do Sul | 50–80 mm, irregularly distributed | Moderate – local flooding and storm damage |
| Central & northeastern Paraná | Over 100 mm in some areas | High – greater chance of urban flooding and landslides |
| Central-western Santa Catarina | 50–80 mm | Moderate – storms with strong winds |
Urban centres in Paraná, in particular, could see rapid water accumulation on streets, especially where drainage is poor or already under strain from previous rains.
How the cyclone forms over Brazil’s coast
The expected cyclone is what meteorologists usually call an extratropical cyclone. Unlike tropical cyclones or hurricanes, these systems form in regions with contrasting air masses, such as the meeting point of very warm and cooler air near the Atlantic coast.
Between Friday and Saturday, a deepening low-pressure centre is likely to organise itself off the southern Brazilian coastline, tapping into heat and moisture stored over land.
As the low strengthens, winds wrap around it, tightening pressure gradients and raising the risk of strong gusts along the coast and over the ocean. Depending on the precise track, coastal areas between southern Brazil and the Southeast could face rough seas, dangerous waves, and squally showers.
For now, specialists do not expect a system on the scale of a hurricane, but the combination of heavy rain, wind, and unstable ground can still trigger landslides in hillside communities and structural damage to weaker buildings or power lines.
What residents can expect on the ground
Conditions will vary widely from city to city, but some common scenarios are likely across the affected states:
- Short, violent thunderstorms with sudden wind gusts and intense lightning.
- Quick spikes in rainfall, leading to flash flooding in low‑lying neighbourhoods.
- Localised power outages due to fallen branches, trees or damaged lines.
- Uncomfortable humidity even after storms, as soils stay moist and temperatures remain relatively high.
Travellers using regional roads and highways, especially in Rio Grande do Sul and Paraná, may face reduced visibility during downpours and the risk of water covering parts of the roadway. Delays in regional flights are also possible if storms line up over major airports.
Why heat and cyclones are linked in southern Brazil
The current pattern over southern Brazil reflects a broader theme: long, hot spells followed by aggressive storm outbreaks. When air temperatures climb towards 40°C and moisture builds near the surface, the atmosphere stores a significant amount of energy. Once a cold front or upper-level disturbance moves in, that energy is quickly released in the form of storms and low‑pressure systems.
In recent years, residents of Rio Grande do Sul and neighbouring states have seen this pattern more often, with episodes of severe hail, damaging winds, and repeated flooding. Meteorologists stress that a single event does not prove a long-term trend, but a cluster of similar events raises questions about how a warming climate may be amplifying extremes.
Practical steps for the coming days
For those living in the areas under alert, a few simple measures can reduce risk during this week of unstable weather:
- Check gutters and drains at home to help water flow away more quickly during cloudbursts.
- Secure loose objects on balconies or in gardens that could be lifted by strong gusts.
- Avoid parking vehicles under large trees during periods of thunderstorm risk.
- Follow alerts from local civil defence agencies and weather services for location‑specific updates.
Fishermen and small boat operators along the southern and southeastern coasts should stay alert for changes in wave forecasts as the cyclone organises offshore. Even if the system remains at sea, it can still send dangerous swells toward beaches and ports.
Understanding a few key meteorological terms
Weather reports for this event often mention “instability areas”, “low pressure” and “irregular rain”. These expressions can sound technical, but they describe everyday experiences during a stormy week.
- Instability areas: Zones where warm, humid air is prone to rising quickly, forming clouds and storms. People on the ground feel this as a sticky, oppressive heat, followed by sudden downpours.
- Low pressure: A region where the air pressure is lower than surrounding areas. Air moves toward the low, rises, and can create clouds, rain and wind. Cyclones are essentially organised low-pressure systems.
- Irregular rain: Rainfall that varies sharply across short distances. One neighbourhood may see torrential rain, while another nearby stays almost dry.
Forecasts for the next few days in Brazil’s South and part of the Southeast combine all three: intense instability, a developing low-pressure centre offshore, and patchy but locally heavy rain. How each city experiences this will depend on the exact path and strength of the cyclone as it spins up along the coast.