Cool maritime air advection and a northwest flow with lingering cloud cover and scattered showers are positioning the maximum temperature in Amsterdam on May 18 near 14–15°C according to the latest KNMI and ECMWF ensemble guidance. This setup suppresses daytime warming well below the mid-May climatological average of 16–18°C, with model spreads driven mainly by variable sunshine duration and shower timing. Early Schiphol observations and updated afternoon model runs will refine whether brief clearing allows a brief push toward 16°C or keeps the peak capped lower. Traders are therefore weighting the closely bunched 14°C and 15°C outcomes most heavily, reflecting genuine uncertainty in the timing and intensity of any breaks in the overcast.