**Persistent summer heat under a strong upper-level ridge positions 100–101°F as the consensus outcome for Austin’s August 15 high, with 102–103°F as the main alternative.** Official National Weather Service guidance and ensemble forecasts show mostly sunny skies, light southerly flow, and minimal cloud cover or moisture, supporting daytime highs near 100–101°F with heat indices reaching 103–106°F. This pattern has delivered consecutive days of 98–101°F readings, consistent with August climatology where normal highs peak near 96–99°F but frequently exceed 100°F under similar subsidence. Model consensus remains tight because steering currents show no significant trough or frontal passage through the 15th, limiting cooling potential. Traders therefore assign roughly 77% combined probability to the 100–103°F range, reflecting the narrow uncertainty band typical when short-range guidance aligns with seasonal norms. Any unexpected increase in afternoon convection or a slight westward shift in the ridge could trim the high into the upper 90s, but current observations and guidance make that outcome less likely.