NESO issues rare summertime plea for more power as temperatures to soar

For only the third time in its history, the British electricity system operator has warned of tight supplies in the summer months.

The National Energy System Operator (NESO) has issued a call-out for additional electricity supply or for energy users to power down on Thursday evening as the UK deals with the third bout of extreme heat in as many months.

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The first and second time such a summertime notice was issued was on back-to-back days during last month's heatwave.

So-called electricity margin notices (EMNs) are a part of balancing expected power supply and demand and do not mean a risk of the lights going off.

They are typically issued only during cold, still snaps when little wind energy is generated and homes and businesses are using a lot of power.

Before June this year, the last time such a notice had been issued was in January 2025. Before then was a cold period in March 2023.

Usually electricity use is lower in the summer months, but use of fans and increased adoption of air conditioning during heatwaves have ramped up demand.

High temperatures in France, from whom Britain imports energy, have meant some nuclear reactors have had to power down as they cannot sufficiently cool.

In recent months, the NESO had set out plans on how to deal with excess supply during this year's hot months in anticipation of the typical lower demand.

Demand on expensive gas

Adding pressure to the electricity supply-demand balance is the fact wind was generating just under 5% of Britain's electricity on Thursday morning, with the majority (37%) coming from gas-fired plants, according to National Grid live data.

On a day in March, a record 50% of British electricity was generated from wind energy.

Gas, in general, is more expensive than renewables but has been even pricier due to the unseasonable demand and the Iran war.

Compounding this is the fact European gas storage facilities, which buy up the fossil fuel when prices are lower, are depleted.

The price of UK wholesale gas is 116 pence per unit, significantly above pre-Iran war levels but below the three-year peak seen in March.

These wholesale costs impact the energy bill price cap set by regulator Ofgem.

And it tends to be gas facilities that power up to meet demand during times of tight supply, thereby setting the overall price of electricity.

It is the most expensive electricity suppliers that dictate the overall price.

Hottest part of the heatwave to come

Temperatures in England could reach as high as 35C or 36C on Thursday and Friday, the Met Office said.

The heat will gradually ease across southern and eastern parts of the UK during the weekend and into next week, it added.

(c) Sky News 2026: NESO issues rare summertime plea for more power as temperatures to soar