**Market-implied odds for San Francisco’s October 9 daily low reflect substantial forecast uncertainty driven by variable marine-layer influence and onshore flow.** Official National Weather Service guidance and short-range models currently project a minimum near 54–58 °F under partly cloudy skies and light-to-moderate southwest winds, consistent with the long-term October average low of 55 °F. However, small changes in the strength of the Pacific high or the timing of any upper-level disturbance can either enhance radiational cooling on clearer nights—pushing readings toward or below 51 °F—or maintain stronger marine moderation that keeps the low in the upper 50s to low 60s. A 70 °F-or-higher minimum would require unusually strong warm-air advection or suppressed onshore flow, an outcome models currently assign low probability. Traders are therefore balancing the risk of modest nocturnal cooling against the typical stabilizing effect of San Francisco’s coastal climate, with resolution hinging on the next 24–48 hours of model updates and observational trends from the National Weather Service.