Hot and cold climate extremes push UK’s energy system to its limits

The arrival of cooler weather is a timely reminder that the UK electricity system must be resilient to the effects of temperature extremes at both ends of the thermometer. The Royal Meteorological Society recently released a report that highlights how recent weather conditions have influenced electricity generation, demand and the infrastructure that connects them. Authored by experts from the society, the Met Office and multiple UK universities, the State of the Climate for the UK Energy Sector Report 2025-26 shows that more energy is being provided by weather-dependent renewable sources.

But high and low temperatures will continue to put the energy grid’s capacity and infrastructure to the test. Data from the National Energy System Operator (Neso) shows that renewable energy formed a higher percentage of overall energy generated in the UK over the reporting period (April 2025 – March 2026) than any other year on record. The proportion coming from the combination of solar and wind increased, providing more than 38 per cent of the nation’s electricity.

The proportion of gas-powered generation reduced to 25 per cent. However, the report highlights how extreme weather tests the resilience of the grid. The conditions that lead to very high and low temperatures create different challenges through increasing electricity demand, limiting generation and damaging network infrastructure. The UK’s energy network is having to adapt to cope with increasingly extreme temperatures. In cold conditions, the network is put under strain due to increased heating demand.

This requires more energy at short notice, increasing reliance on non-renewable sources. For those responsible for balancing the electricity system, including Neso, these weather extremes can create operational challenges. This makes it harder to match energy supply with demand. In early January 2026, strong northerly winds brought cold Arctic air, snow and ice into large parts of the UK. Initially these winds provided up to 20 gigawatts (GW) of power towards the system, a significant proportion of the demand.

But as the freeze reached its peak on the evening of January 6, the wind died down and wind generation fell to less than a quarter of the levels seen in the preceding days. Simultaneously, electricity demand peaked, with the increase in heating needs seeing demand peak an additional 5GW higher than the previous day. Electricity supply and demand have to be kept in balance in real time. When demand rises or available generation falls, the energy system operator can maintain that balance by using additional generators to increase their output, for example.

On this occasion, gas-powered electrical generation filled the gap by providing more than 25GW to the system at it’s peak. This meant the demand was comfortably met, but this was an expensive strategy that meant the operator was paying up to £700 per megawatt-hour (MWh) for this generation. This was due to the higher cost of turning to gas generation, and the need for additional generation at short notice which costs more than generation that can be planned further in advance.

This compares to the usual rate of just over £100 per MWh for the rest of January. At the other end of the spectrum, hot temperatures are increasingly becoming more of a concern for the sector. The summer of 2025 was the warmest on record at the time, with temperatures 1.51°C higher than average. During warmer temperatures, the network operator often limits the amount of power that transmission lines carry around the country to prevent components overheating.

This reduces the risk of lines expanding more with heat which would make them sag and potentially short out on nearby vegetation or structures beneath. Nevertheless, several faults in the network were attributed to heat causing infrastructure damage, leading to power cuts across parts of England, especially during two periods of heatwaves that occurred at the end of June and start of July. In Europe, where temperatures also spiked, nuclear power plants were forced to limit output or shut down altogether because the water used to cool them with, taken from nearby rivers, was too warm.

Increased temperatures and below-average rainfall also increased fire risks. The largest area lost to wildfire burning in the UK since satellite records began included a “mega-fire” in Scotland. Several of these fires led to localised power cuts across the country. The UK’s new grid upgrade plan from the government, which aims to expand and modernise the British grid system to allow for connections to new generation sources and upgrades of current infrastructure, needs to consider the consequences of extreme temperatures.

This includes ensuring that upgraded infrastructure can withstand the extreme heat we are now seeing more regularly in UK summers, as well as ensuring that capacity for transmission of electricity from generation sources to population centres is increased. Delays to electricity grid upgrades risk higher consumer bills as the operator is required to pay wind farms to stop generating because electricity produced cannot be be carried to where it is needed, replacing it with more local gas-powered generation instead.

The resilience of the UK grid has stood up well to the challenges it faced from the weather in the past year. But maintaining that resilience requires continued investment and adaptation as the climate, energy needs of the nation and profile of energy generation all continue to change. James Mollard, is researcher, School of Geosciences, University of Edinburgh Matthew Wright, is DPhil Candidate, Department of Atmospheric Physics, University of Oxford This article first appeared at theconversation.com