Europe Heat Wave Boosts Solar, Sends Power Prices Negative

(Bloomberg) -- The first major heat wave of the season broke temperature records across northwest Europe, triggered water shortages in the UK and has been linked to several deaths in France.

Driven by a persistent high-pressure heat dome, the scorching conditions are expected to continue through Tuesday before easing Wednesday, according to meteorologists and weather models.

The system has pushed away cloud cover across a wide swath of the UK, leading to unusually sunny skies that have further intensified the heat while also boosting solar power generation.

At its peak around midday on Sunday, solar met almost half of the UK’s electricity demand — the highest-ever, according to data from NESO. The surge in renewable output has also weighed on power prices across Europe. In France, hourly power prices traded below zero around 1 p.m. on Tuesday on Epex Spot.

In Italy, where air conditioning is more common, the heat wave is having the opposite effect. Demand on Tuesday is expected to reach 46 gigawatts, the highest since April 7, according to Terna data.

The UK and France recorded their hottest May days on Monday, with temperatures in London and Paris forecast to potentially reach 35C and 33C on Tuesday, according to the UK Met Office and Météo-France.

Over the weekend, increased water demand triggered system failures that left about 800 households in Kent and Sussex without water or experiencing low pressure.

In France, the heat wave has been directly linked to at least two deaths, government spokeswoman Maud Bregeon said Tuesday on TF1 television. At least five people died from drowning, while others died from heat-related causes during sporting events, she said.

Amber alerts for high temperatures are in effect for western Spain, where temperatures could reach 36C on Tuesday. Similar alerts are also active for parts of the UK, including London, east and southeast England, and the Midlands.

(Updates from paragraph two with new details on forecast and power prices)

©2026 Bloomberg L.P.