A strengthening high-pressure system and associated heat dome are driving the current market positioning, with official Met Office guidance and ensemble model runs from the European Centre for Medium-Range Weather Forecasts pointing to peak temperatures of 34–38 °C across London on 23 June. Warm advection from the near-continent, combined with clear skies and light winds, favors rapid daytime warming, while recent amber heat-health alerts reflect growing model consensus that 35 °C will be exceeded. Forecaster updates in the past 48 hours have nudged higher-end scenarios toward 37–38 °C in parts of the southeast, yet spread among runs leaves room for a lower outcome if cloud or a slightly stronger sea breeze develops. Final guidance from the Met Office and updated high-resolution runs on 22 June will be the key catalysts likely to shift trader probabilities before resolution.