Recent model guidance from the European Centre for Medium-Range Weather Forecasts and Météo-France places the most likely daily maximum temperature in Paris on May 18 in the 15–17 °C range, driving the market’s tight clustering around the 15 °C and 16 °C outcomes. Ensemble forecasts highlight modest daytime heating under variable cloud cover and light winds, with limited solar insolation keeping the peak suppressed relative to the mid-May climatological average near 18 °C. Minor differences in predicted timing of any late-afternoon clearing or weak warm advection explain the spread between adjacent brackets, while historical Météo-France records show mid-May maxima commonly falling between 14 °C and 19 °C. Updated model runs and official station observations tomorrow morning will provide the final inputs for verification.