National Weather Service guidance and NOAA ensemble runs currently cluster Dallas’s May 17 high in the mid-to-upper 80s, supporting the near-even market split between the 86–87 °F and 88–89 °F bins. A strengthening upper-level ridge is promoting strong daytime heating under mostly clear skies and 10–15 mph southerly flow, while modest spread in boundary-layer moisture and afternoon cloud timing creates the 1–2 °F uncertainty that keeps the two leading outcomes within a few percentage points. Historical May climatology for Dallas shows average highs near 85 °F, so current model output sits slightly above normal yet remains well below extremes that would favor the 90 °F-plus tail. Updated model runs and afternoon observations will narrow the remaining spread ahead of market resolution.