Price spike (three days running)
Mon 13 Oct · Tue 14 Oct · Wed 15 Oct
Research notes
Figures are for London unless they say otherwise.
What happened
- London evening peaks of 58.6p (Mon, 18:30), 57.7p (Tue, 18:30) and 59.2p (Wed, 17:30); up to 68.5p in Northern Scotland.
- The whole day was dear, not just the peak: daily averages of 23.3 to 23.8p and overnight lows no lower than 15p.
Likely causes
- Almost no wind for six days. Elexon-metered wind averaged 0.9GW on Sun 12 Oct, 1.4GW on Mon 13, 2.4GW on Tue 14, 2.9GW on Wed 15, 2.6GW on Thu 16 and 1.4GW on Fri 17. At 18:30 on Mon 13 Oct it was under 1.0GW. Five of the eight calmest days of the whole Sep to Dec period fall in this one stretch. (confirmed by source: Elexon FUELHH, 12 to 17 Oct; ranking is my calculation)
- Gas plants filled the gap. Gas averaged 20.2GW on Mon and 20.8GW on Tue, the two highest daily averages of the four months, peaking at 23.9GW on Tue. When gas is supplying that much, the most expensive gas plants set the price. (figures confirmed by source: same Elexon query; the price mechanism is inference)
- The weather was "anticyclonic gloom": high pressure parked over the UK with light winds and thick low cloud. The Met Office published an explainer on it on 13 Oct, and its 14 Oct forecast said high pressure was "remaining firmly in charge this week" with "light winds". (confirmed by source: Met Office, What is anticyclonic gloom?, 13 Oct; Met Office week ahead, 14 Oct)
- The gloom hit solar too. Daily solar peaks were 2.4 to 2.8GW, about half the Oct median of 4.9GW. (confirmed by source: PVLive)
- It was not a gas price shock. The UK gas price sat at about 80p a therm all week (79.5 to 81.5p), so the spike came from how much gas was being burned, not what it cost. (confirmed by source: Utility Regulator NI weekly market report, week of 13 Oct, gas prices credited there to Oil Market Journal)
- The same calm hit Ireland: the all-island market's day-ahead price rose from £117/MWh on Mon to £173/MWh on Wed. That is a separate market, but it shows the lull was regional. (confirmed by source: same Utility Regulator report)
A word on "dunkelflaute"
- This was a textbook dunkelflaute (dark, still weather). GB News attributed that word to Met Office meteorologists (GB News), but neither Met Office article above uses it or mentions energy. Safe to use the word as a description; don't attribute it to the Met Office.
Wider context that week
- NESO's Winter Outlook, published four days earlier on 9 Oct, had forecast the most comfortable winter margins since 2019/20. (NESO)
- The gloom broke at the weekend: wind was back to 13.7GW on Sun 19 Oct (Elexon), as the Met Office had forecast Atlantic fronts arriving "during the second half of the weekend".
Confidence
High on the cause (a multi-day wind and solar lull with record gas burn for the period). No journalist's report of the GB price was found, so the explanation rests on data and the Met Office, not on a market source.
Gaps
No Reuters, Bloomberg or Montel piece on GB prices for these dates. I could not check whether NESO issued any capacity market notice (the notices site did not load its list); I found no report of one. Actual GB day-ahead baseload figures not found.