Official temperature observations from National Weather Service stations in Los Angeles recorded a daily high of 76-77°F on September 17, anchoring the market's near-certain consensus on that bin. Late-summer marine layer influence and stable high-pressure patterns kept afternoon maxima in this narrow range, consistent with regional climatology for mid-September. With the full 24-hour observation window now closed, trader sentiment rests on verified data rather than model forecasts, sharply reducing implied probability for adjacent temperature brackets. Minor revisions to the official record could theoretically occur during quality-control checks, though such adjustments are infrequent and usually small.