**Official observations from the Charles de Gaulle Airport weather station—the market's designated source—confirm Paris's highest temperature on April 17 reached exactly 21°C, driving trader consensus to 100% implied probability on that outcome.** This aligns with Météo-France's preliminary data amid mild spring conditions featuring high-pressure influence, light southerly winds, and partial cloud cover that capped daytime heating. Pre-event ECMWF ensemble forecasts and national model runs had converged on highs of 20-21°C, matching the observed peak around mid-afternoon. With the event passed and data published, markets reflect verified measurements; realistic challenges are minimal, limited to infrequent quality-control revisions uncovering sensor anomalies, though historical precedents show such adjustments affect less than 0.5°C in 99% of cases. Traders await no further updates as resolution nears.