**Recent northerly winds and persistent showers from an incoming frontal system are the main drivers keeping Istanbul's overnight minimum on October 17 clustered near 11–13 °C across most model runs.** Cooler maritime air advection, combined with widespread cloud cover and light-to-moderate rainfall (expected totals 10–30 mm), limits daytime heating and enhances radiative cooling overnight, favoring the lower end of the range. Ensemble spread remains notable because small differences in wind speed, cloud timing, or exact frontal passage can shift the low by 2–3 °C, which is why market-implied odds sit near 33–34 % for each integer from 8 °C to 16 °C while the broad tails (≤7 °C or ≥17 °C) each price at 50 %. Updated high-resolution runs from ECMWF, GFS, and regional models over the next 24–48 hours will be the key catalysts for any re-pricing ahead of resolution.