Recent ECMWF and KNMI ensemble runs keep Amsterdam’s maximum temperature tightly clustered around the 14–15 °C threshold today, driving the near-even split in market-implied probabilities between those two outcomes. A cool northwesterly maritime air mass and variable cloud cover are the dominant controls: modest differences in afternoon sunshine duration—rather than large-scale temperature advection—determine whether the daily peak reaches 15 °C or remains capped at 14 °C. Historical May climatology shows averages near 16–18 °C, so persistent low-level stratus and limited insolation explain the downward shift in trader expectations. Updated afternoon model guidance and real-time observations from Schiphol will resolve the remaining uncertainty before market settlement.