The ocean is warming, but the atmosphere has only begun to respond.
Com a chegada de junho, o Brasil inaugura oficialmente seu inverno meteorológico ao mesmo tempo em que o Pacífico equatorial aquece de forma crescente, anunciando um episódio de El Niño em plena configuração. O fenômeno, ainda em acoplamento entre oceano e atmosfera, já exibe anomalias suficientes para classificação moderada e deve receber declaração oficial da NOAA em breve. Enquanto o Sul do país enfrenta frentes quentes e chuvas expressivas, o Centro-Oeste mergulha na seca sazonal — dois mundos climáticos separados por uma fronteira invisível, mas determinante. O inverno de 2026 não será apenas frio: será moldado por forças que se gestam a milhares de quilômetros de distância.
- O El Niño está se intensificando em junho, com anomalias de temperatura no Pacífico já atingindo o limiar moderado por seis semanas consecutivas — a declaração oficial da NOAA pode vir a qualquer momento.
- No Paraná e em partes de Santa Catarina, sistemas vindos da Argentina e do Paraguai ameaçam provocar chuvas muito acima da média, com risco real de enchentes e alagamentos.
- O Rio Grande do Sul, historicamente o estado mais frio e chuvoso do Brasil em junho, deve registrar precipitações próximas ou ligeiramente abaixo da média, com exceção do norte do estado.
- Modelos climáticos internacionais divergem sobre as temperaturas: o europeu aponta para um Sul mais frio, enquanto o americano projeta calor acima da média — a MetSul aposta em um junho mais ameno do que maio.
- A expectativa é de menos noites de geada severa do que em anos historicamente rigorosos, com a primeira quinzena mais quente e possíveis incursões de frio mais intenso na segunda metade do mês.
Junho chega marcando o início oficial do inverno brasileiro — a estação meteorológica que abrange junho, julho e agosto — enquanto o Pacífico equatorial aquece de maneira crescente e começa a redesenhar o clima do continente. No Sul do Brasil, especialmente no Rio Grande do Sul, junho é historicamente um dos meses mais frios e chuvosos: em Porto Alegre, as mínimas médias giram em torno de 11,3°C e a precipitação média chega a 130,4 milímetros, tornando-o o quarto mês mais chuvoso do ano. Já em São Paulo e no Centro-Oeste, o padrão se inverte: junho marca o início da estação seca, com chuvas caindo para menos da metade desse volume.
Essa divisão regional reflete uma dinâmica atmosférica profunda. No Sul, frentes quentes que avançam dos trópicos colidem com massas de ar frio, gerando chuvas intensas. No interior central, a seca se aprofunda e estende sua influência até países vizinhos como Argentina e Uruguai, que também se beneficiam da umidade redirecionada.
Sobre esse cenário sazonal já complexo, sobrepõe-se o El Niño de 2026. As temperaturas na superfície do oceano na região de monitoramento oficial já registram anomalia de +1,0°C pela metodologia de 30 anos, com o fenômeno presente por seis semanas consecutivas. O acoplamento entre oceano e atmosfera ainda está em curso, e a declaração oficial da NOAA é esperada para meados de junho.
As previsões de chuva para o mês refletem essa combinação de fatores. O norte do Rio Grande do Sul deve ver precipitações acima da média, enquanto o restante do estado fica próximo ao normal. Paraná e partes de Santa Catarina enfrentam risco elevado de chuvas excessivas e inundações. Estados como Mato Grosso do Sul, São Paulo e Minas Gerais também podem registrar volumes acima do esperado para a estação seca.
Quanto às temperaturas, os modelos internacionais divergem, mas a avaliação da MetSul aponta para um junho mais ameno do que maio, sem a severidade de anos como 2016. A primeira metade do mês tende a ser mais quente no Sul, enquanto uma massa de ar de trajetória oceânica resfria o Sudeste. Na segunda quinzena, uma ou duas incursões de frio mais intenso são possíveis. O resultado esperado é um inverno reconhecível em seu caráter — noites frias, manhãs de geada ocasional —, mas suavizado por um oceano distante que já começou a ditar suas condições.
June arrives as Brazil's winter officially begins, and across the equatorial Pacific, the ocean is warming in ways that will reshape weather patterns across the continent for months to come. The month marks the opening of the three-month winter season—June, July, and August—though the astronomical winter itself doesn't begin until June 21st. Historically, June is one of the coldest months of the year in southern Brazil, often bringing intense cold snaps, frost, and occasionally snow. In Porto Alegre, the capital of Rio Grande do Sul, average minimum temperatures hover around 11.3 degrees Celsius, with average highs near 20.3 degrees. The monthly average sits at 14.8 degrees, making it the second-coldest month of the year based on climate data from 1991 to 2020. Yet the region is not dry. June typically brings substantial rainfall to Rio Grande do Sul—averaging 130.4 millimeters in Porto Alegre, the fourth-wettest month in the city's annual cycle. Meanwhile, just to the north, the pattern inverts. In São Paulo and across central Brazil, June marks the onset of the dry season, with rainfall dropping sharply to just 59.7 millimeters on average.
This regional split in precipitation reflects a deeper atmospheric pattern. As winter settles in, warm fronts—masses of warm air pushing northward from the tropics—frequently collide with cold air masses over southern Brazil, producing heavy and sometimes excessive rainfall. The state of Rio Grande do Sul sees more of these warm fronts in June than in any other month. Meanwhile, the dry interior of central Brazil extends its influence southward, drawing moisture away from the center and toward the southern latitudes, benefiting parts of Argentina and Uruguay as well as the southern Brazilian states.
But June 2026 arrives with an additional player in the atmospheric game: El Niño. The equatorial Pacific has begun warming, and the phenomenon is intensifying as the month progresses. According to the U.S. National Oceanic and Atmospheric Administration (NOAA), ocean surface temperatures in the Niño 3.4 region—the official monitoring zone for El Niño—showed an anomaly of plus 0.5 degrees Celsius in the most recent weekly bulletin. By the traditional monitoring method, which averages 30 years of climate data, the anomaly has already reached plus 1.0 degree, meeting the threshold for a moderate El Niño and showing the characteristic signature of the phenomenon for six consecutive weeks. The ocean is warming, but the atmosphere has only begun to respond. As June unfolds, the coupling between ocean and atmosphere is expected to fully configure, likely triggering NOAA's official declaration of El Niño around mid-month or later.
The rainfall forecast for June reflects both seasonal patterns and the emerging influence of El Niño. Most of Rio Grande do Sul is expected to see rainfall near or slightly below its historical average, despite the month's typical wetness. However, the northern half of the state could receive above-average precipitation. Further north, in Paraná and parts of Santa Catarina, the outlook shifts dramatically. Systems evolving from northeastern Argentina and Paraguay are expected to bring well-above-average rainfall to these states, with some areas of Paraná facing risks of flooding and inundation. Central-West states like Mato Grosso do Sul, along with São Paulo, parts of Minas Gerais, and Rio de Janeiro, may also see precipitation above their dry-season norms.
Temperature forecasts for June reveal disagreement among international climate models. The European model projects cooler conditions from São Paulo southward, while the U.S. model indicates above-average temperatures across much of central and southern Brazil. MetSul Meteorologia's assessment, weighing these models and other data, suggests June will not be as cold as May was. The probability of a brutally cold month with an exceptionally high number of sub-zero nights—like June 2016 experienced—is very low. Instead, the expectation is for above-average temperatures across much of the Center-West, with Mato Grosso and Goiás likely running warmer than historical norms. Mato Grosso do Sul will sit closer to average, with some areas experiencing below-average readings, particularly in the south. The Southeast should see temperatures near to above average, especially from central São Paulo northward and across Minas Gerais. Southern areas and eastern São Paulo will hover near historical averages. In the South, temperatures are expected to be close to or slightly above average in the northern portions, while Rio Grande do Sul will likely see readings near the long-term mean, with some areas dipping below.
What this means in practice is that while June remains fundamentally a cold month—nights will still be cold, as they always are in winter—the number of severely freezing nights should decline, and afternoons should feel more pleasant than in particularly harsh years. The first half of June may run warmer than average in the South while the Southeast experiences cooler conditions due to a cold air mass with an oceanic trajectory passing east of the southern region. Around mid-month and into the second half, one or two stronger incursions of cold air are possible, bringing the second half of the month colder than the first. The stage is set for a June that is winter in name and in many of its characteristics, but tempered by an ocean warming far away and the complex dance of atmospheric systems that will define the season ahead.
Notable Quotes
The probability of a brutally cold month with an exceptionally high number of sub-zero nights, like June 2016 experienced, is very low.— MetSul Meteorologia analysis
The Hearth Conversation Another angle on the story
Why does June matter so much for understanding what's coming in the rest of the winter?
June is the opening act. It sets the pattern. The way moisture flows, where cold air masses collide with warm ones, how the ocean begins to influence the atmosphere—all of that gets established in June and tends to persist. El Niño doesn't flip a switch; it's a slow coupling. June is when we see it beginning to take hold.
So the warming ocean in the Pacific actually changes how rain falls in southern Brazil?
Exactly. El Niño shifts the jet stream, changes where systems develop and how they move. It's not direct—it's not like the warm water reaches Brazil. But the atmospheric response to that warmth ripples across the hemisphere. In this case, it's one factor among many, but it matters.
The forecast says most of Rio Grande do Sul will be drier than usual for June, even though June is normally wet. That seems counterintuitive.
It does. Normally, June is one of the wettest months there. But this year, the models suggest the systems won't be as organized or as frequent. The northern part of the state might get soaked, but the rest will be closer to average or below. It's a regional split, not a blanket pattern.
What about the temperature divergence between the European and American models?
They're looking at the same data but weighing different factors differently. The European model is more pessimistic about warmth in the south. The American model sees above-average heat across much of the center and south. MetSul's read is that neither extreme is likely—it'll be warmer than May but not dramatically so. Fewer brutal nights, but still winter.
If June is the second-coldest month of the year in Porto Alegre, does "above average" still mean people need heavy coats?
Absolutely. Above average for June is still winter. You're talking about average highs around 20 degrees Celsius. The point isn't that it'll be warm; it's that it won't be as brutally cold as it could be. Fewer nights below freezing. More afternoons where you don't need three layers. That's what above average means in June.