September recorded the highest rainfall volume in the South and Southeast regions in 17 years, driven by the El Niño phenomenon and the constant passage of cold fronts.
The river basins in the South and Southeast regions experienced an atypical climate scenario last month, accumulating the highest volume of precipitation for the period in nearly two decades. The intensification of the El Niño phenomenon, characterized by the warming of Pacific Ocean waters, directly altered the country’s rainfall patterns, significantly benefiting water reserves essential for national energy security.
According to analyses presented by the ONS (National Electric System Operator), the rapid advance of cold fronts fueled frequent storms and caused temperatures to drop below historical averages across much of the territory. This rainy outlook significantly strengthened the production capacity of hydroelectric plants, bringing relief to the SIN (National Interconnected System) following concerning drought periods in previous cycles.
Positive impact on renewable energy generation
Excessive rainfall and consistent winds brought historic milestones for the Brazilian energy matrix throughout September. The ONS recorded unprecedented marks in renewable energy production, driven by both hydrological potential and the growth of wind and solar generation in different regions of the country. On September 2nd, the system registered a historic hourly peak of 45,624 MW from clean sources, meeting more than half of the SIN‘s instantaneous demand.
The technical bulletin released during the PMO (Monthly Operation Program) highlighted:
Favorable meteorological conditions during the period ensured a remarkable performance from clean energy sources, reinforcing the robustness and versatility of the national electric matrix in the face of climate variations.
The South region, with impressive Natural Inflow Energy levels that reached marks exceeding 250% of the historical average, became an electricity-exporting zone for other parts of the country. In contrast, the North and Northeast regions maintained modest rainfall indices, requiring a joint effort in integration and reservoir management to balance energy supply.
Future outlook and the scenario for October
The current climate dynamics reinforce the trend of a strong El Niño throughout the spring and summer, dictating the next steps for Brazilian energy operations. For October, sector projections indicate continued above-average rainfall in the South basins, while the Southeast and Central-West are expected to record levels within the normal range, with higher precipitation concentration in the first fortnight.
With reservoirs at secure levels—especially in the South, which ends the cycle with nearly its full capacity filled—the clean energy sector enters the last quarter of the year with greater predictability. The challenge for the coming months will be the efficient management of the interconnection between regions to compensate for climate asymmetries and sustain the sustainable growth of the economy.
