Latest Met Office guidance and ensemble models indicate a daytime maximum near 23–24°C in London on September 30, supported by southeasterly flow advecting milder maritime air while increasing cloud cover and scattered showers limit peak insolation. Recent runs show slight cooling from the 26°C expected on the 29th as a frontal boundary approaches, with wind speeds of 10–15 mph reducing boundary-layer mixing. Historical late-September averages hover around 18–20°C, so current conditions reflect a mild anomaly. Traders assign the highest implied probability (49%) to 23°C because model consensus clusters there, with only modest upside risk if clearer breaks develop. Updated NWP runs and observational trends will refine resolution criteria before markets close.