**Forecast models currently point to an overnight low in Austin on September 17, 2026, in the mid-to-upper 70s°F, with consensus centered around 75–78°F.** This range aligns with the closely bunched market probabilities (roughly 19–20% each for the 72–73°F, 74–75°F, 76–77°F, and 78–79°F bins), reflecting genuine uncertainty rather than a single dominant outcome. Key drivers include persistent southerly to southeasterly flow off the Gulf of Mexico, which maintains elevated dew points and limits nocturnal radiative cooling. High daytime maxima near 95–100°F further warm the boundary layer, while variable cloud cover—ranging from partly to mostly cloudy with a slight storm chance—can trap longwave radiation and raise minimum temperatures by several degrees compared to clear-sky scenarios. Subtle differences in model timing of any moisture or wind shifts create the spread across those narrow 2°F bins. Historical September climatology for Austin shows average lows near 70°F, but the current warm, humid pattern has kept recent overnight readings several degrees above that baseline. Updated National Weather Service and global model runs over the next 24–48 hours will likely narrow the distribution by refining cloud and wind forecasts ahead of the overnight period.