Cold front ends heat wave in São Paulo state, bringing storms, hail risk and a sharp temperature drop

Heat wave comes to an end

Since Thursday, August 27, a heat wave driven by a hot, dry air mass has covered São Paulo state and much of central Brazil, suppressing cloud formation. On Monday, August 31 — the last day of August — the state capital remained hot with sun between clouds. According to the Emergency Management Center (CGE), temperatures ranged from 19°C to 32°C with 35% humidity, while the National Meteorology Institute (Inmet) reported slightly different figures — 18°C to 27°C with humidity up to 100%. On Sunday, August 30, Civil Defense issued an alert for rain, strong winds and possible hail in the western, southern and eastern parts of the capital.

Cold front brings storms

On Tuesday, September 1, a cold front moved in from the coast, triggering rain showers, thunderstorms, wind gusts and a sharp afternoon temperature drop. According to CGE, the capital's temperature on Tuesday was expected to range from 11°C to 25°C with 50–100% humidity, while Inmet forecast 15°C to 22°C. Afternoon showers were expected to intensify, bringing lightning and wind gusts above 50 km/h. Inmet issued a yellow alert for storms across several states — Paraná, Santa Catarina, São Paulo, Mato Grosso do Sul, Minas Gerais, Rio de Janeiro and Mato Grosso.

In the southern region, where heavy rain and hail have continued since August 27, storms have already caused two deaths. A brief lull was expected there on Monday, but storms were set to resume Wednesday across southern and central Paraná, all of Santa Catarina, and central-northern Rio Grande do Sul.

Santo André and the Greater ABC region

In Santo André, part of the Greater ABC region near São Paulo, Tuesday's forecast called for changeable weather — from sun with clouds to overcast skies with morning rain, afternoon storms and a rainy night; a high of 23°C and a low of 16°C. Wednesday, September 2, was expected to bring sunnier weather with a few clouds and brief rain during the day and night. This contrasts sharply with August 29, when the entire Greater ABC region saw hot, dry weather with no rain — Santo André recorded a high of 32°C, while São Caetano posted the region's highest reading, 33°C.

What comes next

According to Inmet, cold, rainy weather was set to continue in the capital on Wednesday, September 2, with temperatures between 12°C and 18°C, while CGE forecast an even lower minimum of 8°C. On Thursday, September 3, sunshine was expected to return, though with a cold, foggy morning — a low of 9°C, warming to 25°C during the day. On Friday, September 4, temperatures were expected to climb again to 28°C, with dry conditions and humidity dropping as low as 25%.