**Current forecasts from the Met Office and other models indicate a maximum of 21–23°C for London on September 2, 2026, under mostly overcast skies with light southwesterly winds and only isolated light showers or drizzle possible.** This aligns closely with the historical average high of ~21.6°C at London Heathrow for the date and explains why the market-implied probabilities cluster tightly around 21°C (32.5%) and 22°C (36.5%), with lower odds for 20°C or 23°C. Persistent cloud cover is the main limiting factor, reducing solar insolation and preventing stronger daytime warming despite mild airflow from the southwest. Model consensus shows limited diurnal range, with afternoon peaks unlikely to exceed the mid-20s°C range even in clearer spells. Recent model runs have not introduced significant warm-air advection or clearing trends that would push readings higher, keeping the outlook stable near seasonal norms. Traders are weighting the slight edge toward 22°C because some guidance (including certain Met Office regional outlooks) allows for brief breaks in cloud that could support that level, while the risk of more persistent overcast or light rain keeps 21°C competitive. Resolution will depend on the official highest reading at the designated London station, with little scope for outliers given the benign synoptic pattern.