Hottest summer on record.
Winter was supposed to be the hard bit.
The Met Office confirmed on 1 September that summer 2026 was provisionally the hottest the UK has recorded. Mean temperature 16.5C, 1.9C above average, beating last year. The grid was built on the assumption that winter is the stress test. It has just had a summer of them.
🌡️ The summer in numbers
38.1C at Kew on 13 August, the hottest day. 54 weather stations set new daily records. Sixth sunniest summer with 622 hours of sun. Rainfall 77% of normal.
The Met Office says a summer like this was made about 130 times more likely by climate change. The five warmest summers are all since 2003. 1976 is now seventh.
⚡ What the grid learned
Two Electricity Margin Notices in June. A frequency wobble on 23 June. Imports bought at nearly twenty times the normal price. Ofgem now investigating.
Solar carried the afternoons. Household panels saved an estimated £86.7m across 26 heatwave days. Then the sun set with the country still at 28C and everything switched to gas and cables.
Hot, still evenings were the hard days. That is new. The operator plans for a cold January. It now needs to plan for a warm August too.
🏠 What it means for this winter
The gas that was burned keeping summer evenings running was gas that did not go into storage. UK storage was under 50% full heading into September.
That feeds straight into the October cap and the January forecasts. Summer heat becomes a winter bill.
The lever that works in both seasons is the same. Use less between 5pm and 8pm. Get paid to do it.
Britain has had five heatwaves, a record solar month and a grid investigation in one summer. Anyone still describing flexibility as a winter product has not been paying attention.