Southern Brazil Braces for Rising Temperatures as Summer Begins
A warming trend is forecast for the coming days in Southern Brazil, coinciding with the start of summer in the Southern Hemisphere on December 21, 2025, at 12:03 pm. Residents of Santa Catarina (SC) can expect increasingly warm conditions, with potential for isolated thunderstorms later in the week.
Regional Forecasting Approach
The weather forecasts for Santa Catarina are based on a climatological approach, grouping regions by rainfall and temperature similarities rather than strictly adhering to traditional political-administrative divisions. This method, according to a statement from the forecasting team, “allows a more precise approach for weather forecasting and climate monitoring purposes.”
Week Ahead Weather Outlook
Wednesday, December 17th: Conditions will be firm and sunny across all regions of Santa Catarina. Temperatures will be milder than recent days, reaching highs of 24 to 29°C in the afternoon. Winds will be south/southeast, shifting to east/northeast, and remain weak to moderate. A high pressure system and associated dry air mass are currently positioned over the southern coast of Brazil.
Thursday, December 18th: The state will experience steady sunshine throughout the day. Temperatures will be mild at dawn, dipping to a minimum of 4°C, with a possibility of isolated frost in the higher elevations of the Southern Plateau. Daytime temperatures will climb, with maximums of 27 to 33°C expected in the afternoon. Winds will be northeast, weak to moderate, with gusts along the South Coast. The high pressure system maintaining the dry air mass will persist.
Friday, December 19th: Santa Catarina will see continued sunshine with some cloud cover. A mass of dry air is moving towards the ocean, contributing to rising temperatures. Highs are expected to reach or exceed 30°C. Winds will be northeast, weak to moderate, with gusts along the South Coast.
Saturday, December 20th: Sunshine and scattered clouds are predicted for Santa Catarina, with a chance of isolated rain between Greater Florianópolis and the northern part of the state, particularly in the evening, due to maritime circulation. Temperatures will remain high, exceeding 30°C, and the air will feel stuffy. Northeast winds will be weak to moderate, with gusts between Greater Florianópolis and Litoral Sul, reaching 40 to 60 km/h.
Sunday, December 21st: The official start of summer will bring sun and heat to Santa Catarina, but also increased instability and the potential for isolated thunderstorms in the afternoon, especially in the west and south of the state. These storms are linked to low pressure areas in Rio Grande do Sul (RS). Highs will again be near or above 30°C, with continued stuffy air. Winds will be northeast, weak to moderate, with gusts.
The forecast is provided by Gilsânia Cruz, a meteorologist with Epagri/Ciram. Residents are advised to stay hydrated and take precautions against the heat, particularly during peak hours.
