Forecast uncertainty from ensemble numerical weather prediction models, including runs from Taiwan's Central Weather Administration, underpins the tight clustering of market-implied odds around 27–29°C for Taipei's June 15 high. Persistent mei-yu frontal influences and associated cloud cover are limiting daytime insolation and convective heating in this subtropical regime, while scattered showers and moderate northeasterly flow further moderate peak temperatures near long-term June averages of 30–32°C. Urban heat-island effects and boundary-layer humidity add local variability that widens model spread, preventing stronger consensus on whether conditions will reach the upper end of the range. Updated model cycles and official guidance on precipitation timing remain the key near-term catalysts that could shift sentiment.