LONDON, July 9, 2026, 14:04 BST
- NESO sent out an Electricity Margin Notice for Thursday evening, calling on the market to provide more generation or more flexibility.
- The operator said the notice isn’t a blackout warning and customer supplies aren’t at risk.
- The alert is out as Britain sees its third heatwave this year, with heat cutting some power generation in Europe.
Great Britain’s electricity system operator called on generators and major consumers to boost supply Thursday evening as hot weather tightened the gap between demand and available power. The Electricity Margin Notice, or EMN, is in force from 6:30 p.m. to 10:30 p.m. BST, The Independent said.
The move is notable because such notices are not common in summer. Sky News said this is just the third summertime warning ever from the operator, following two similar ones last month during the heatwave, as high temperatures boosted demand from fans and air conditioning at a time when power use is normally down.
An EMN signals the market, it’s not an instruction to cut usage. NESO says this notice signals the system could need more generation and asks firms to say what they can bring online. It does not mean blackouts are coming.
NESO said Thursday evening could see “tight electricity margins” as high temperatures across Europe cut into generation. The operator said it will keep an eye on the situation and step in if needed to keep supplies secure. NESO said there was “no risk” to customer electricity. The Guardian
The Met Office says another spell of heat is hitting the UK, making this the third heatwave so far this year. Southern England is set for several days in the low 30s Celsius, and some areas could get as high as 34 to 35C later this week.
Officials have expanded their warnings about the hot weather. UKHSA said amber heat-health alerts will last until 9 p.m. Sunday in the North West, Yorkshire and the Humber, the Midlands, the East of England, London, the South West and the South East. Dr Agostinho Sousa at UKHSA said ongoing high temperatures can lead to “serious negative health outcomes,” mostly for older people and those with health problems. Gov
It’s not just demand. Jess Ralston, energy analyst at the Energy and Climate Intelligence Unit, said heat is taking a toll on the power system, making it tougher to cool gas plants and forcing France’s nuclear plants to cut output when they can’t cool reactors. “This supply crunch comes at the same time that demand is rising from air con and fans,” she said. Energy & Climate Intelligence Unit
EDF in France has already had to curb some nuclear output during the latest European heatwave as warmer river water limits reactor cooling. Britain usually relies on interconnectors to bring in power from continental Europe when it makes sense on price and supply.
Low wind is another pressure point. Sky, using National Grid live data, reported wind made up just under 5% of Britain’s power early Thursday. Gas stations covered around 37%—a pricier setup with wholesale gas high.
The new notice comes after a late-June heatwave broke records. The Met Office said England hit a new provisional daily high for June with 37.7C at Lingwood, Strumpshaw Hill, on June 26, topping the mark set in 1976.
NESO faces cost and strain risks if heat sticks around, not a sudden supply loss. If wind stays light, French nuclear still tight or heat drags on, NESO could buy extra, fast power from gas plants or imports; if more capacity shows up, it can pull back the notice like it did in June.
