Weather forecast: autumn 2026 starts warm, but the first real cold snap is on the horizon
If you were hoping for that crisp, cool weather to kick off the first week of autumn, you'll have to hold your horses a little longer. Autumn 2026 officially began this Friday, 20 March, but the weather forecast for the next few days is predicting plenty of heat – a scenario that's a far cry from what we used to see in the past.
At least, that's what the latest weather maps are showing. The season of falling leaves is arriving with above-average temperatures across most of the country. Remember that familiar "friagem" (cold spell) that started making an appearance at the end of summer? Well, it's taken a break. If you live in the Southeast or Central-West, for example, you'll still be facing days where thermometers easily top 30°C, as if summer is stubbornly refusing to leave.
Persistent heat and patchy rain
What stands out about this change of season is its unpredictability. The weather and climate forecast suggests rainfall will be unevenly distributed. While the South and parts of São Paulo might still see more consistent rain in the first few weeks, in the interior of the Northeast and northern Minas Gerais, water will remain scarce. And that's a concern, because it's been a while since we've seen a "neat" 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 block. In practice, this means a mass of warm air remains stationary, preventing those cold fronts – which usually bring in proper autumn conditions – from arriving straight away.
So when does the cold actually arrive?
The big question on everyone's lips: where's the cold? Well, I've been following the forecast models and the date is already on our radar. The first intense cold of autumn – the kind that has you digging out your coat and enjoying a hot cuppa in the late afternoon – is expected to arrive in the first week of April. More specifically, between the 6th and 9th.
During this period, a polar air mass is set to send temperatures plummeting in the South and cause a significant thermal shock in the Southeast. But don't expect a gradual change. The trend is for us to go from sweltering heat close to 35°C straight down to 15°C in a matter of hours. This kind of abrupt transition is typical of Brazilian autumn, but this year it promises to be more intense.
- South (RS, SC, PR): Be extra vigilant! The turn of the month will already bring a drop in temperature. Get those 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 earnest around the 7th or 8th of April, accompanied by that biting wind that cuts right through you.
- 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 from years of tracking the climate - weather forecast, it's that Brazilian autumn has become a box of surprises. Nothing is as it was a decade ago. We need to keep a close eye on regular updates, because this back-and-forth of hot and cold air masses catches everyone off guard.
So, the advice is: make the most of this last weekend of March with that lingering heat, because just around the corner, that intense cold will come knocking. And when it does, it won't be just to say hello – it'll be here to stay. Love weather? For now, the only love affair might be with your blanket, because it's going to be that kind of weather outside.