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The cold air mass advancing over Santa Catarina from Monday night, April 27, is expected to cause a sharp drop in temperatures in all regions, with greater intensity in the Grande Oeste and Planalto Sul, increasing the risk of thermal discomfort and worsening respiratory and cardiovascular diseases
Santa Catarina’s Civil Defense issued a new meteorological observation at 7:50 PM this Sunday, April 26, 2026, to warn about the arrival of a cold air mass in the state. According to the agency, the strongest change will be felt between Monday night, the 27th, and Tuesday morning, the 28th, when temperatures are expected to drop sharply in all regions of Santa Catarina.
The warning draws attention to the rapid change in weather and its direct impact on the population’s routine. In addition to the generalized drop in temperatures, the agency points to a low to moderate risk of occurrences related to thermal discomfort and the worsening of respiratory and cardiovascular diseases, a scenario that tends to weigh more heavily precisely in the areas where the cooling will be most intense.
Cold air mass arrives with force and changes the weather throughout the state
The cold air mass predicted by the Civil Defense begins to influence Santa Catarina from Monday night. Before that, throughout the 27th, the south quadrant wind gains strength and starts pushing temperatures down between late afternoon and nighttime.
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The effect will not be restricted to a single part of the state. The meteorological observation highlights that the drop affects all regions, although the most intense impact should be concentrated in the Grande Oeste and Planalto Sul, where the cold air is expected to advance more strongly during Tuesday’s early morning.
The numbers that explain the magnitude of the temperature drop
In the Planalto Sul, the forecast indicates lows between 2°C and 6°C in the early morning and dawn of Tuesday, April 28. It is in this part of the state that the lowest temperature range predicted in the observation issued by the Civil Defense appears.
In the Grande Oeste, thermometers should register between 5°C and 10°C. In areas of the South Coast, temperatures may occasionally drop below 10°C. These numbers show that the cooling will not be localized and should reach different regions with enough intensity to change the thermal pattern in a few hours.
What happens between Monday night and Tuesday morning
The most critical interval of the alert is well defined. According to the meteorological observation, temperatures begin to fall throughout Monday night, but the strongest decline occurs mainly during Tuesday’s early morning.
This detail is important because it indicates a rapid change. It is not a gradual cooling over several days, but a sharp drop in a short period, which increases the potential for thermal discomfort and requires extra attention precisely during the hours of lowest temperature.
Why Planalto Sul and Grande Oeste are at the center of the alert
The Civil Defense itself highlights that the most intense drop should affect the Grande Oeste and Planalto Sul. This places these two areas at the center of the meteorological warning, as they concentrate the lowest temperatures predicted in the state.
In the case of Planalto Sul, the minimum range of up to 2°C makes the region the most sensitive within the observation issued at 7:50 PM. In the Grande Oeste, although the predicted values are higher, the cooling also appears significant and sufficient to produce a relevant impact between night and early morning.
What changes in practice for the Santa Catarina population
The main practical change will be a stronger sensation of cold in a very short interval. With the sharp drop predicted for all regions, the state enters a scenario of greater thermal discomfort precisely between Monday night and Tuesday morning, when the heat loss will be most felt.
In addition, the Civil Defense warns of the worsening of respiratory and cardiovascular diseases. This increases the weight of the warning because the phenomenon ceases to be merely a change in weather and also comes to represent a factor of attention for health, especially among people more sensitive to cold.
The role of the south wind in the advance of cold air
The meteorological warning also highlights the action of the south quadrant wind throughout Monday. This wind reinforcement is one of the elements that helps push the cold air mass over Santa Catarina and accelerate the drop in temperatures between the end of the day and the following dawn.
In practice, this explains why the decline appears so marked in the bulletin. The advance of cold air does not occur in isolation, but is associated with a change in the wind pattern, which favors the faster entry of this cooling over the state.
Why the 7:50 PM observation gains weight at this moment
The 7:50 PM update reinforces the Civil Defense’s monitoring at a time when the temperature change already has a well-defined window to begin. The agency delimits not only the most critical period, but also the regions that should feel the impact of the cold air mass with greater intensity.
This gives the warning important practical weight. The observation organizes the scenario with time, date, and areas of greatest attention, allowing the population to better understand where the cooling will be strongest and when it should happen.
What the alert shows about the coming days in Santa Catarina
Even though it is an observation focused on the period between Monday night and Tuesday morning, the bulletin makes it clear that Santa Catarina enters an important thermal turning point at the end of April.
The advance of the cold air mass changes temperature behavior in all regions and places part of the state in a range of more intense cold already in the first hours of the 28th.
The highlight for minimums of up to 2°C in Planalto Sul, combined with the risk of thermal discomfort and worsening of diseases, shows that the alert goes beyond a simple cold forecast. It indicates a significant, rapid cooling episode with the potential for direct impact on the routine of Santa Catarina.
In your region, has this cold air mass already changed the thermal sensation or should the strongest drop really be felt between Monday night and Tuesday morning?
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