Trader sentiment for Taipei's May 18 high temperature centers on short-term forecast uncertainty, with outcomes tightly clustered between 30°C and 32°C reflecting ensemble model spread in numerical weather prediction. Current guidance shows southerly monsoon flow delivering warm, moist air typical of late-spring patterns, while afternoon sea-breeze convergence and scattered convection introduce a 2–3°C range in peak readings. The 31°C lead at 24.5% arises from mean solutions balancing moderate insolation against urban heat-island amplification in the Taipei Basin. Higher probabilities for 33°C or above hinge on clearer skies and stronger downslope warming, whereas lower outcomes depend on increased cloud cover or a passing weak front suppressing temperatures closer to the seasonal 29–30°C baseline. Updated model runs and official agency guidance over the next 48 hours will refine these thresholds ahead of market resolution.