**Official forecasts from the National Weather Service and supporting models point to an overnight low in the upper 70s for Dallas on August 27, 2026, driving the tight clustering of market-implied odds around 78–83 °F.** Persistent extreme heat (daytime highs near or above 100 °F) has kept recent overnight minima elevated, but a wind shift to northeast at 5–10 mph and mostly clear skies after earlier shower chances favor radiational cooling under building high pressure. This setup typically allows temperatures to drop into the upper 70s rather than remaining in the low 80s, consistent with NWS guidance of ~78 °F and analogous late-August patterns. Historical averages for the date sit near 76 °F, yet the current anomalous warmth narrows the realistic range. Model spread in boundary-layer moisture, exact cloud timing, and subtle advection explains why 78–79 °F, 80–81 °F, and 82–83 °F outcomes trade so closely—small forecast revisions can shift the minimum by 2–4 °F. Lower odds on 75 °F or below reflect the limited cooling potential from the ongoing heat dome, while higher bins remain discounted absent major pattern changes. Traders are effectively pricing the consensus upper-70s outcome against normal forecast uncertainty in a high-stakes, rapidly resolving weather market.