Recent National Weather Service guidance and ensemble model runs point to a daytime high near 66–68 °F in San Francisco on May 17, driven by a persistent marine layer and coastal stratus that restricts solar heating along the immediate shoreline. This pattern aligns with typical May climatology, in which onshore flow from the Pacific keeps maximum temperatures well below inland values and produces only modest afternoon warming. Trader consensus for the 68 °F-or-higher outcome reflects the upper edge of current forecast spreads, while probabilities for 66–67 °F capture the most likely central tendency given stable atmospheric conditions and no strong high-pressure ridge expected to clear the clouds. Updated model runs tonight and the final official reading at San Francisco International Airport will determine resolution within the narrow temperature bands.