The ongoing European heatwave, with daytime highs forecast to reach 30–40°C across northern France into the weekend, serves as the dominant driver keeping implied probabilities tightly clustered around 16–18°C for Paris’s overnight low on August 9. Recent model runs from ECMWF and Météo-France show minimal nocturnal cooling under persistent high pressure and light winds, pushing minimums several degrees above the long-term August average of 15–16°C while urban heat-island effects in central Paris further limit radiative losses. Subtle differences among leading outcomes hinge on small forecast variations in cloud cover, boundary-layer mixing, and any late-arriving Atlantic moisture that could enhance or suppress the diurnal range. Updated guidance expected over the next 24–48 hours will clarify whether the minimum settles near 17°C or edges toward 16°C or 18°C.