Santa Catarina residents are preparing for the official start of summer wiht a forecast calling for high temperatures and humidity through Christmas Eve. The heatwave, beginning this weekend, is expected to see temperatures climb above 30 degrees Celsius (86 Fahrenheit) statewide, with increased risks for vulnerable populations-notably the elderly and those without adequate access to cooling.Epagri/Ciram meteorologist Marcelo Martins is tracking the system, which is influenced by both a warm air mass and an approaching weather trough.
Hot and Humid Weekend Forecast for Santa Catarina
Summer Begins in the Southern Hemisphere: December 21, 2025, at 12:03 PM
Santa Catarina state is bracing for a warm and humid weekend as summer officially begins in the Southern Hemisphere. Temperatures are expected to climb above 30 degrees Celsius (86 degrees Fahrenheit) with high humidity, creating uncomfortable conditions. The forecast also includes the potential for isolated showers and thunderstorms, particularly in the western and coastal regions.
Saturday, December 20th will see mostly sunny skies across Santa Catarina, with a chance of isolated rainfall in the Greater Florianópolis area and the northern part of the state, especially during the evening hours due to onshore winds. Winds will be light to moderate from the northeast, with gusts reaching 40 to 50 kilometers per hour (25 to 31 mph) between Greater Florianópolis and the southern coastline. A mass of warm air is currently influencing the region’s weather patterns.
The start of summer on Sunday, December 21st, promises continued heat and sunshine, but with increasing instability. Isolated thunderstorms are likely to develop in the afternoon, particularly in the western, central-western, and southwestern parts of the state. Greater Florianópolis and northern Santa Catarina can expect scattered showers, especially in the morning and evening, due to ongoing maritime circulation. Winds will shift to the northeast to northwest, remaining light to moderate, with gusts between 40 and 60 kilometers per hour (25 to 37 mph) along the Greater Florianópolis and southern coastal areas. Both a mass of warm air and a trough are contributing to the changing conditions.
Looking ahead to Monday and Tuesday, December 22nd and 23rd, the forecast calls for variable cloud cover with sunny breaks. Isolated showers are possible during the afternoon and early evening, especially in the western and central-western regions, as instability from Rio Grande do Sul state and an approaching cold front move closer. Localized thunderstorms are not ruled out. Temperatures will remain high, consistently above 30 degrees Celsius (86 degrees Fahrenheit) with continued humidity. Winds will be from the northeast, shifting to the south on Tuesday, and will be light to moderate with gusts.
Wednesday, December 24th, will bring partly cloudy to overcast skies with a continued chance of isolated showers throughout the day. Temperatures are expected to decrease slightly compared to previous days. Winds will be from the southwest to south, light to moderate with gusts.
Marcelo Martins – Meteorologist (Epagri/Ciram)
The map presented on this site does not adhere to the political-administrative divisions of the IBGE. It was developed based on climatological criteria, grouping the regions of Santa Catarina according to similarities in rainfall and temperature patterns, allowing for a more precise approach for weather forecasting and climate monitoring.
