The market-implied odds reflect official National Weather Service observations confirming a daily maximum of 70-71°F in San Francisco on August 17, driven by the final post-event verification from primary surface stations. This outcome aligns with typical late-summer conditions moderated by the marine layer and prevailing westerly flow, which suppress extreme highs relative to inland areas. Trader positioning incorporates the certainty of archived meteorological data, including thermometer readings and quality-controlled records that meet resolution criteria for the specified temperature bin. Minor uncertainty remains around potential station-specific revisions or microclimate differences, though historical precedent shows such adjustments rarely exceed 1-2°F after initial reporting. No further forecast updates will shift the result, as the date has concluded.