Forecasts from the National Weather Service and multiple models indicate a high near 99°F for Dallas on September 20, with mostly sunny skies, southerly flow, and only a 20% afternoon thunderstorm chance that may limit peak heating slightly. This consensus supports the market's strongest implied probability on 98-99°F, as persistent late-summer warmth and lack of strong frontal passage keep readings well above the long-term average high of roughly 89°F. Limited model spread and stable guidance over recent days reduce the odds of outliers like 96-97°F or 100°F+, though any earlier convection or increased cloud cover could nudge the outcome lower. Updated NWS briefings and model runs ahead of the date remain the key near-term catalysts.