Phenomenon has a 63% chance of occurring in the 2nd half of this year; survey considered the impact of El Niños since 2015
Months with a “very strong” El Niño had the highest average weight of tariff flags on the electricity bill, according to a survey by Poder360 with data from the (National Electric Power Agency) and the (National Oceanic and Atmospheric Administration), the United States climate agency.
During these periods, the additional amount charged by the brands corresponded, on average, to 7.6% of the basic residential electricity tariff. The percentage is 62.1% higher than that recorded in months without El Niño, when the average weight of flags was 4.7%.
The calculation compares the additional amount charged per kWh by the tariff flags with the national average of the residential base tariff for each month. The analysis considers the months with El Niño records since January 2015, when the tariff flag system came into force. When the flag is green, there is no additional charge, and the weight considered is 0%.
The impact of El Niños on the electricity bill, reveals the survey, varied depending on the intensity of the phenomenon.
- In months classified as “very strong” El Niño, the average weight of the flag was 7.6%;
- In the months of “moderate” El Niño, it was 5.3%;
- In months without El Niño, the average was 4.7%;
- The “weak” and “strong” El Niños had, on average, cheaper rates: additional 3.5% and 2.7%, respectively.
The data indicates that El Niño can put pressure on the electricity bill, but not automatically. The phenomenon changes the rainfall regime and, therefore, can affect the generation of hydroelectric plants.
When there is less water available in reservoirs or hydrological conditions worsen, the electrical system may need to activate more thermal plants, which produce more expensive energy. This additional cost reaches the consumer through tariff flags.
The relationship, however, is not direct in all years. The effect depends on where and when the rains occur, the level of the reservoirs before the phenomenon, the demand for energy, the supply of other sources and the system’s operating decisions. Therefore, El Niños of similar intensity may have different impacts on the tariff.
NOAA reported this Thursday (June 11, 2026) that El Niño conditions are already present in the Equatorial Pacific and should strengthen during the Northern Hemisphere winter of 2026-2027. According to the agency, there is a 63% chance of the phenomenon reaching intensity “very strong” between November 2026 and January 2027, which would place it among the biggest events in the historical series that began in 1950.
In Brazil, the effect of El Niño on the electricity bill will depend mainly on the volume of rainfall in the regions where the hydroelectric plants are located. On Wednesday (June 10), the government informed a meeting of the (Electricity Sector Monitoring Committee) that the rainfall that supplies the reservoirs is below average in May in the Southeast/Central-West, Northeast and North regions. The South was the exception, with above-average volume.
For June 2026, the forecast also indicates a scenario of caution. According to data presented to CMSE, the volume of water that should reach the country’s hydroelectric plants could be between 67% and 76% of the historical average. In the worst case scenario, it would be the 4th lowest level in 96 years. The ONS (National Electric System Operator) stated that it will continue to monitor rain and reservoir conditions to define how the electrical system will be operated.
The current tariff flag for the month of June is yellow. In this range, there is an increase of R$1.885 for every 100 kWh consumed.
METHODOLOGY
The calculation compares the added value (per kWh) of the tariff flag for a given month – with or without El Niño – with the average base tariff charged by distributors in the same period. The “weight” referred to in the infographic refers to the % of the value added by the brand to the base tariff. To classify the intensity of El Niños, the parameters established by NOAA were used.
