Official observations from National Weather Service stations in the Austin area recorded a daily maximum of 98–99°F on September 22, 2026, under partly cloudy skies with light easterly winds and dew points in the low 70s that limited further heating. This outcome aligns with the strong late-summer pattern of above-normal temperatures across central Texas, where September 2026 mean highs have run 10–12°F above the 1991–2020 climatology of roughly 90°F. Model guidance and surface analyses showed no significant frontal passage or increased cloud cover that would have suppressed the peak, while heat-index values approached 105°F during afternoon hours. Traders placed near-certain weight on the 98–99°F bin because preliminary climate summaries and station data converged on that narrow range well before market close. Only an unexpected revision to the official Austin-Bergstrom or Camp Mabry reading—unlikely given multiple confirming reports—could shift the outcome.