**Current forecasts from the National Weather Service and major models point to a low near 56–57°F for San Francisco on August 31, aligning with the two leading market outcomes (58–59°F at 39.5% and 56–57°F at 32.0%).** San Francisco’s late-summer climate is dominated by the marine layer and persistent onshore flow from the Pacific, which caps daytime highs in the low-to-mid 60s and prevents nocturnal temperatures from dropping sharply. The historical average low for the date is 56.1°F, with recent years typically ranging from the mid-50s to low 60s under similar conditions. No significant shift in the 500-mb pattern or coastal upwelling is expected to alter this regime over the next 48 hours, keeping extreme tails (66°F+, or 47°F and below) at lower implied probabilities. Model consensus remains tight, with only minor variations in cloud cover and wind speed that could nudge the overnight minimum by 1–2°F either way. Traders are therefore pricing the outcome as a narrow range around climatology rather than a departure driven by unusual synoptic features.