Recent Met Office and European ensemble forecasts have converged on a London daytime maximum of exactly 15 °C for May 16, driven by persistent northerly airflow that has kept readings 2–3 °C below the mid-May climatological average of 17–18 °C. Stable high pressure, light winds, and mostly sunny intervals have limited afternoon heating, anchoring trader consensus at 100 % implied probability for 15 °C. A modest late-day shift toward clearer skies or a brief southerly wind component remains the main scenario that could nudge readings to 16 °C, though current model guidance assigns this low likelihood before the daily peak is observed.