Official forecasts from the Met Office and supporting models indicate London will reach a daily maximum near 21°C on October 1 under high pressure, sunny intervals, and light westerly winds, placing it several degrees above the 1991–2020 average high of 17.9°C. Trader consensus, reflected in the 58.5% implied probability for 21°C and 35% for 20°C, aligns with this guidance and limited model spread, while lower odds for 22°C or higher account for minor uncertainties in afternoon cloud cover or localized variations. Recent observational data showing morning temperatures climbing steadily toward 19–20°C further reinforce expectations for a peak in the low 20s Celsius range before cooling overnight.