Weather Forecast: Autumn 2026 Starts with Heat, and the First Cold Snap Already Has a Date
If you were hoping for that lovely chilly weather right in the first week of autumn, you'll have to hold your horses a bit longer. Autumn 2026 officially kicked off this Friday, March 20, but the weather forecast for the next few days is for plenty of heat and a scenario that's completely different from what we used to see.
At least, that's what the latest weather maps show. The season of falling leaves is set to arrive with above-average temperatures across most of the country. Remember that well-known "cold spell" that started making an appearance at the end of summer? Well, it's taken a break. Folks in the Southeast and Central-West, for example, will still face days where thermometers easily hit over 30°C, as if summer is stubbornly refusing to leave.
Persistent heat and irregular rainfall
What stands out about this change of season is the unpredictability. The weather and climate forecast suggests rainfall will be poorly distributed. While the South and parts of São Paulo might see more consistent rain in the first few weeks, the interior of the Northeast and northern Minas Gerais will continue to see scarce water. And that's a concern, because it's been a while since we've seen a "standard" rainfall pattern like we used to.
To give you an idea, running the forecast models on the platforms we use to track wind and pressure, the scenarios show a persistent atmospheric blocking pattern. In practical terms, this means a hot air mass gets stuck in place, preventing those cold fronts that typically bring true autumn weather from arriving right away.
So, when does the cold actually arrive?
The big question on everyone's mind: where's the cold? Well, I've been following the forecast models, and the date is already on the radar. The first real cold snap of autumn, the kind that makes you dig out a jacket from the closet and even enjoy a hot coffee in the late afternoon, is predicted to arrive in the first week of April. More specifically, between the 6th and 9th.
During this period, a polar air mass is expected to send temperatures plummeting in the South and cause a significant thermal shock in the Southeast. But look, don't expect a gradual change. The trend is for us to go from a sweltering near-35°C straight down to 15°C in a matter of hours. This type of abrupt transition is classic for Brazilian autumn, but this year it promises to be more intense.
- South (RS, SC, PR): Pay close attention! The end of the month already starts with a drop in temperature. Get the blankets and heavier coats ready for the first week of April. Frost could appear in the highland areas.
- Southeast (SP, RJ, MG, ES): The forecast is for heat to dominate the last days of March. The cold is only expected to arrive in full force around the 7th or 8th of April, bringing that biting, chilly wind.
- Central-West and Northeast: The change will be felt less intensely, but nights will become milder, especially in higher altitude areas like the Chapada Diamantina and the Brasília region.
If there's one thing I've learned in all these years of following the climate - weather forecast, it's that Brazilian autumn has become a box of surprises. Nothing is like it was ten years ago. We have to keep an eye on constant updates, because this back-and-forth of hot and cold air masses tends to catch everyone off guard.
So, here's the tip: enjoy this last weekend of March with that lingering heat, because soon enough, that intense cold will be knocking on the door. And when it knocks, it won't just be to say hello. It'll be here to stay. The weather for romance? For now, it's only love for a warm blanket, because it's going to be that kind of weather outside.