An approaching heatwave driven by a strong subtropical ridge has positioned elevated overnight minimums as the dominant factor in trader positioning for Paris on June 18. Météo-France forecasts indicate a warm air mass with daytime peaks near 36°C and nighttime lows around 20°C under clear skies and light winds, limiting radiative cooling. Ensemble models show modest spread in boundary-layer temperatures, supporting the market's emphasis on 18–19°C outcomes as the most probable range for the official minimum recorded at reference stations. Urban heat island effects in central Paris further reduce the likelihood of sub-17°C readings, while recent model runs have not introduced cooler anomalies that would shift implied probabilities toward lower bins. Updated guidance expected overnight will clarify any adjustments to these thermal profiles ahead of market resolution.