Recent Met Office and ECMWF ensemble guidance, combined with high pressure over northwest Europe and modest Atlantic flow, positions 21–22°C as the most probable maximum temperature range for London on August 21. These conditions favor partly cloudy skies with limited daytime heating, keeping afternoon peaks near seasonal late-August climatology of 21–22°C rather than allowing stronger warming. Updated model runs show little support for 24°C or higher thresholds, aligning with the market’s heavy weighting toward 20–22°C outcomes. Traders are monitoring the next official forecast updates for any shifts in cloud cover or wind patterns that could nudge the peak slightly lower or higher before resolution.