Heatwaves are becoming an unavoidable reality. As temperatures rise, society depends more heavily on electricity, and on the grid that supplies it.
The impact is straightforward, cooling demand increases across homes, offices, hospitals, commercial buildings and public infrastructure. At the same time, high ambient temperatures reduce the ability of electrical equipment to release heat.
The result is a pressure from two sides on the grid: demand rises while the operating margin of grid assets decreases.
This no longer happens occasionaly. Copernicus reports that heatwaves in Europe are becoming more frequent and severe. In 2025, the number of days with strong or very strong heat stress was the second highest on record, lasting 25 days and affecting a large part of the continent. [1]
Heat does not only increase electricity consumption. It also changes when and where electricity is used.
Cooling can create sharp afternoon and evening peaks, especially in areas where residential and commercial demand overlap. During heatwaves in France in 2025, evening electricity demand rose by around 25% above typical off-season levels, despite relatively low air-conditioning ownership. [2]
The impact is often local, particularly in dense urban areas. A country may have enough generation available overall while individual neighbourhoods, feeders or substations are operating close to their limits.
Urban areas are especially exposed because buildings retain heat and cooling demand continues after sunset. This creates longer periods of high consumption and gives grid equipment less time to cool between peaks.
Higher demand, lower grid capability
Heat does not only affect demand. It also affects the grid itself.
Transformers, cables and power lines rely on the surrounding air and ground to dissipate heat. When temperatures rise, equipment operates with less safety margin and may age faster or even breakdown.
A UK government assessment found that extreme heat can reduce the carrying capacity of lines and cables and accelerate transformer degradation. Distribution transformers may be particularly vulnerable because they often have less redundancy and less advanced cooling, especially in dense urban areas. [3]
This does not mean that every heatwave will cause widespread outages. ENTSO-E’s Summer Outlook 2026 found that Europe’s overall electricity adequacy remained favourable. [4]
However, a stable European power system does not mean that every local distribution network is operating without stress.
The main challenge for distribution system operators is knowing where pressure is building before it becomes an outage.
DSOs need to understand which assets and areas are most exposed, how local demand responds to heat and where the available operating margin is already limited.
During a heatwave, operators should be able to answer practical questions:
Which parts of the grid are approaching their limits?
Which assets are repeatedly exposed to high temperatures and high loading?
Where is voltage quality deteriorating?
Where is immediate intervention required?
Which locations should be prioritised for future reinforcement?
The goal is not to generate more alarms. It is to enable better decisions.
Combining smart meter data, substation measurements, weather forecasts and asset information can provide a clearer view of how heat affects the local grid. Analytics can then help identify abnormal conditions, prioritise field activity and distinguish temporary demand peaks from recurring capacity problems.
Heatwave resilience will still require physical investment. Some assets will need to be replaced, and parts of the grid will need to be reinforced. However, better operational visibility can help DSOs decide where those investments are most urgent and where existing infrastructure can still be used safely.
Each heatwave also provides valuable operational evidence. It shows which assets were under pressure, how long the stress lasted and where the same problems are likely to return.
The DSOs best prepared for a hotter climate will be those that understand where their networks are under stress and act before local problems become customer outages.
Thaora helps DSOs turn data from smart meters, substations and grid assets into a clearer operational view of the distribution network.
By identifying emerging constraints, abnormal conditions and recurring stress points, Thaora supports more informed operational decisions and better investment prioritisation.
In a hotter climate, grid resilience starts with visibility.
Discover how Thaora can help you understand where your distribution grid is under pressure, before that pressure becomes an outage.
