Recent Met Office and ECMWF ensemble forecasts have converged on a London maximum of 18°C for May 17 under partly cloudy skies and moderate westerly flow, anchoring trader consensus at near-certainty for that exact outcome. Official surface analyses place the day within a transitional spring regime where Atlantic influences typically limit afternoon heating to the 16–18°C range, consistent with historical May climatology. Minor model adjustments or unexpected clearing could still push readings to 19°C, though current observational trends and steering patterns make such shifts unlikely before resolution.