Northeasterly monsoon winds are the dominant driver behind current market odds clustered around 28–30°C for Taipei’s September 11 high, as they advect moist air and favor cloud cover with scattered showers that limit daytime heating. Official guidance from Taiwan’s Central Weather Administration and ensemble models indicate afternoon temperatures peaking near 29°C amid 60–80% rain probabilities, consistent with climatological September norms of 28–31°C highs under similar flow patterns. Minor model spread on shower timing and intensity creates the tight distribution between 28°C and 30°C, while lower probabilities for 31°C or above reflect suppressed insolation and evaporative cooling. Fresh model runs and CWA briefings over the next 48 hours will refine land-sea breeze interactions and moisture convergence that ultimately determine the daily maximum.