Autumn 2026 Weather Forecast: A Hot Start with the First Intense Cold Snap Already on the Horizon
If you were hoping for those pleasant chilly days right at the start of autumn, you'll need to hold your horses for a bit longer. Autumn 2026 officially kicked off this Friday, March 20th, but the weather forecast for the coming days points to plenty of heat and a scenario that's far from what we used to see back in the day.
At least, that's what the latest weather maps are showing. The season of falling leaves will arrive with above-average temperatures across most of the country. Remember that familiar “cold snap” that was already making an appearance at the end of summer? Well, it's taken a break. Folks in the Southeast and Central-West, for instance, will still face days where thermometers easily hit above 30°C, as if summer is stubbornly refusing to leave.
Persistent Heat and Irregular Rainfall
What's striking about this seasonal transition is the irregularity. The weather and climate forecast indicates that rainfall will be poorly distributed. While the South and parts of São Paulo might still see more consistent rain in the first few weeks, the interior of the Northeast and northern Minas Gerais will continue to experience water scarcity. And that's a concern, because it's been a while since we've seen a “proper” 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 usually bring the true autumn weather right off the bat.
And the Cold, When Does It Really Arrive?
The big question on everyone's mind: where's the cold? Well, I've been monitoring the forecast models, and the date is already on the radar. The first intense cold snap of autumn—the kind that has us pulling jackets out of the closet and even enjoying a hot cup of tea in the late afternoon—is expected to arrive in the first week of April. More specifically, between the 6th and the 9th.
During this period, a polar air mass is expected to drop temperatures 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 scorching heat near 35°C straight down to 15°C within hours. This kind of abrupt transition is typical of Brazilian autumn, but this year promises to be more intense.
- South (RS, SC, PR): Extra caution needed! The end of the month already starts with a temperature drop. Get your blankets and heavier jackets ready for the first week of April. Frost may appear in the mountainous areas.
- Southeast (SP, RJ, MG, ES): The forecast indicates heat will dominate the last days of March. The cold should only arrive in force around April 7th or 8th, bringing that chilling wind that cuts right through you.
- Central-West and Northeast: The change will be felt less intensely, but nights will become cooler, especially in higher altitude areas like Chapada Diamantina and the Brasília region.
If there's one thing I've learned following the weather - weather forecast all these years, it's that Brazilian autumn has become a box of surprises. Nothing is quite what it was a decade ago. We need to keep an eye on constant updates, because this back-and-forth of hot and cold air masses ends up catching everyone off guard.
So, the tip is: enjoy this last weekend of March with that lingering heat, because soon enough, that intense cold will come knocking. And when it knocks, it won't just be to say hello—it will be here to stay. Weather for love? For now, only if it's love for your blanket, because the weather outside is going to be something else.