Recent model guidance from the Met Office and European Centre for Medium-Range Weather Forecasts has converged on a London maximum temperature of 15–16 °C for May 18, driven by a northerly flow of cooler Atlantic air and increasing cloud cover that limits daytime heating. Mid-May climatology places the long-term average high near 16–17 °C, so current conditions reflect modest suppression from scattered showers and light winds rather than strong high-pressure dominance. Ensemble spreads remain narrow, keeping probabilities tightly clustered around 14–16 °C outcomes while reducing odds for warmer thresholds above 17 °C. Traders are watching the next 48-hour model runs for any shift in frontal timing or clearer breaks that could nudge the afternoon peak slightly higher or lower.