Powerful Polar Air Mass Set to Send Temperatures Plunging, Bringing the Year’s Most Intense Cold Snap

A strong polar air mass is forecast to move over Brazil between May 8 and May 12, bringing the coldest weather of the year so far to the country’s south-central regions. According to projections from Brazil’s National Institute of Meteorology (Inmet) and Climatempo, the system is expected to cause a sharp drop in temperatures, with frost, subzero readings, and even winter precipitation possible in the South.

Meteorologists say the cold front will be especially intense in the Southern states, where mountain and high-altitude areas may see temperatures fall below 0°C between May 10 and May 12. Those conditions increase the likelihood of moderate to strong frost, which could affect crops and native vegetation. In the highest parts of the Serra Gaúcha and Serra Catarinense, the combination of lingering moisture and very cold air may also create the chance of frozen rain or graupel during the early morning hours.

The cold is not expected to remain confined to the South. Forecast maps indicate that the polar air will advance inland and reach the Southeast and Center-West. In the Southeast, including Greater São Paulo, the cooling trend is likely to be reinforced by moist winds coming from the ocean. Minimum temperatures in the early mornings of May 11 and May 12 could drop to around 10°C, with gray skies and a stronger cold-feel sensation during the day.

In the Center-West, the arrival of the polar air could trigger a brief episode of “friagem,” or a sudden cold spell, in Mato Grosso do Sul, Mato Grosso, and southern Goiás. That would temporarily interrupt the usual heat across the region. Before the cold surge arrives, central Brazil is expected to remain very dry, adding to concerns about the rapid shift in weather conditions and the falling humidity.

Authorities and weather specialists are warning that the abrupt temperature change could pose risks to second-crop agriculture and increase thermal stress on native vegetation. The dry air and sharp cooling may create challenging conditions for rural areas, especially where crops are already vulnerable.

By contrast, the North and Northeast are not expected to be affected by the polar air mass. These regions should remain under the influence of tropical weather systems and continue to receive the heaviest rainfall in the country during the period. Temperatures there are expected to stay high, highlighting the strong atmospheric divide shaping Brazil’s climate in early May.