**Trader consensus at 100% implied probability for a 25°C high in Paris on September 5, 2026, stems from convergent short-range forecasts issued by Météo-France and global models such as GFS and ECMWF.** These show a daytime maximum reaching exactly 25°C under a mix of morning cloud cover transitioning to mostly clear skies, with light northwest winds limiting mixing and urban heat retention. Current surface observations around midday align with this trajectory, tracking near the long-term September 5 average high of 23°C while avoiding the warmer anomalies seen in recent years. Resolution hinges on the official daily maximum recorded at the Paris-Montsouris station; minor deviations could arise from localized urban effects or final-hour model adjustments, but the tight clustering of guidance leaves little room for outcomes outside 24–26°C.