**Unseasonably warm southeasterly flow and clearing skies after morning cloud have lifted London temperatures toward 25–27°C on September 29, 2026, according to Met Office and ensemble forecasts.** This late-September warmth stems from a deep Atlantic low drawing milder air northward, with afternoon peaks expected near 26°C at Heathrow and 27°C in parts of the southeast—well above typical late-month averages. Historical context shows the date’s record at 28.1°C (2011), yet current model consensus and live observations cluster around 24–26°C maxima. Traders have priced 24°C as the clear leader at 64.5% implied probability, reflecting caution over exact official station readings, potential for slight model over-forecasting, and resolution criteria tied to a specific measurement source. Upcoming afternoon updates from the Met Office will likely determine whether probabilities shift toward 25°C or 26°C.