Recent Met Office guidance indicates a minimum of 19°C for London on July 28 under a warm, settled pattern with daytime highs near 29°C, following an early-July heatwave that peaked at 35°C. Ensemble model spreads and minor variations in overnight cloud cover, wind, and boundary-layer mixing create tight clustering around 18–20°C outcomes, explaining the near-even 36% market-implied probabilities. Clearer skies would favor slightly lower readings via enhanced radiational cooling, while any increase in humidity or light winds could hold minima near 20°C. Updated short-range runs and satellite observations over the next 48 hours will narrow the range ahead of resolution.