Recent short-range forecast ensembles for Taipei on May 18 indicate a likely daily maximum near 31–33 °C under subtropical spring high pressure, with limited moisture and modest afternoon heating. Minor differences in model guidance on boundary-layer mixing, cloud development, and local sea-breeze timing create the tight clustering of market-implied odds around 32 °C (29.5 %), 31 °C (23.5 %), and 33 °C (22.5 %). Taiwan Central Weather Administration runs and regional ensembles show only small spreads in peak surface temperature, consistent with historical May climatology where daytime maxima commonly reach the low-30s without organized rainfall. Traders are therefore weighting the narrow scientific uncertainty in afternoon convective inhibition and wind speed rather than any larger-scale pattern shift.