**Persistent late-summer heat and clear, calm conditions produced an unusually warm overnight minimum in Dallas on September 13, 2026.** Official observations recorded a daily low of 83°F (with a high near 100°F), well above the 1991–2020 climatological average of 71°F. South winds of 5–10 mph, high humidity, and mostly clear skies prevented significant radiational cooling, keeping temperatures in the low 80s through the night. Multiple real-time sources, including National Weather Service data streams and station reports, converged on this value, giving traders near-certainty in the 82–83°F band once the calendar day ended. The dominant market positioning reflects the completed observation window and the absence of measurement uncertainty once official data were available. Only an improbable revision to the preliminary climatological record or a station-specific discrepancy could shift the outcome, scenarios with negligible probability given the consistency across reporting networks.