Overview

• A heat wave active from September 18 to 22 is lifting temperatures well above average across much of the country, with interior cities forecast to reach or top 40°C, according to Climatempo and Inmet.
• Inmet issued low-humidity alerts in Piauí, with Teresina projected between 35°C and 39°C and afternoon dryness near 20% to 30%, raising health and fire concerns.
• Rio Grande do Sul faces the highest immediate risk from Friday through Sunday, with heavy rain, hail potential, and very strong gusts as an extratropical cyclone develops offshore, and winds locally exceeding 100 km/h are possible.
• Forecasts indicate a powerful cold front from September 22 to 24 will sweep the South and advance into the Southeast, Center-West and parts of the North, triggering storms, strong winds and a rapid temperature drop.
• São Paulo is expected to heat up through the weekend with highs near 33°C before a sharp cool-down and risk of heavy rain and gusty winds early next week, while Rio de Janeiro may approach 40°C before the front brings a quick turn to cooler conditions.