Dutch TTF futures, Europe's main gas benchmark, surged to over €65 per megawatt-hour on Thursday — the highest level since March — extending a rally that has pushed prices up more than 130% since the start of the year.

The rally comes in the middle of another summer heatwave across Europe, and that heat is part of the reason the coming winter is shaping up to be an expensive one.

Record temperatures are pushing up electricity demand, while drought and heat curb hydro and nuclear generation. That is forcing gas-fired power stations to fill part of the gap, just as Europe should be putting more gas into storage.

Gas prices remain well below the €350/MWh peak reached during the 2022 energy crisis triggered by Russia's invasion of Ukraine. But Europe is heading into winter with inventories depleted and little room for another supply shock.

Why European gas prices are rising again