Energy experts say periods of prolonged high temperatures typically lead to a sharp rise in electricity consumption, particularly during the hottest hours of the day when cooling equipment is operating at full capacity.

Although Portugal’s electricity grid is designed to cope with periods of increased demand, exceptionally hot weather can place additional pressure on infrastructure, especially in areas where consumption peaks simultaneously.

Not a nationwide blackout

The greatest risk is not a nationwide blackout but isolated interruptions affecting specific neighbourhoods or local distribution networks if equipment becomes overloaded or experiences technical faults.

High temperatures can also reduce the efficiency of electrical infrastructure. Transformers, power lines and other equipment operate less effectively during extreme heat, while prolonged exposure to high temperatures can increase the likelihood of failures requiring temporary repairs.

Portugal has experienced similar situations during previous heatwaves, with localised outages occurring in some regions as electricity demand reached seasonal highs.

Efficient use of electricity

Energy specialists are encouraging consumers to use electricity efficiently where possible, particularly during peak afternoon and early evening periods. Measures such as setting air conditioning to moderate temperatures, limiting the use of high-consumption appliances simultaneously and improving home ventilation can help reduce pressure on the network.

The warning comes as much of mainland Portugal remains under high-temperature alerts, with inland districts forecast to exceed 40°C over the coming days. Authorities continue to advise residents to stay hydrated, avoid unnecessary outdoor activity during the hottest part of the day and check on vulnerable family members and neighbours.

While Portugal’s electricity system has significant capacity to manage periods of intense demand, experts say responsible energy use during extreme weather can help minimise the risk of local disruptions as the heatwave continues.