National Weather Service forecasts for San Francisco on September 27 project a daytime high near 61–65°F, driven by persistent onshore westerly flow and a strengthening marine layer that suppresses warming along the coast. This setup aligns with typical late-September climatology, where average highs hover around 70°F but cool anomalies often develop from upwelling and stratus. Model consensus from NWS and private sources shows limited warming potential, supporting market-implied odds favoring the 64–67°F range while capping chances for 72°F or higher absent a sharp offshore shift. Updated guidance ahead of the weekend will clarify any adjustments to this coastal cooling pattern.