A polar continental air mass is moving southward over Brazil, triggering the first cold wave of 2026 [1].

The weather system poses a significant risk to agriculture and public health across the South, Southeast, and Central-West regions. Sub-zero temperatures and potential frost may impact crop yields and urban infrastructure in these areas.

The cold front has been active since May 8 and is expected to persist until May 13, 2026 [1]. Meteorological data indicates the system is affecting 12 Brazilian states [2], including São Paulo and Mato Grosso do Sul [1].

Temperatures in the affected regions are dropping below 0 °C [2]. This sudden plunge in temperature is the result of an intense polar continental air mass moving over the central-south of the country [1, 3].

There is some variation in timing regarding the peak of the system. Some reports indicate the peak occurred Monday, May 11, while other data suggests the lowest temperatures will arrive Tuesday, May 12, 2026 [4].

Local authorities in the South and Southeast are monitoring the frost risk, as the polar mass continues its transit across the interior. The system is expected to lose strength following the May 13 window [3].

“the first cold wave of 2026”

The arrival of a polar mass in May indicates a sharp seasonal transition that can disrupt regional logistics and agriculture. Because the system spans 12 states, the economic impact of potential frost damage to crops in the South and Central-West could be substantial, while urban centers like São Paulo face sudden spikes in energy demand for heating.