The market's decisive 100% consensus on a 19°C high for Helsinki on May 16 stems directly from official observations at Helsinki-Vantaa Airport Station confirming that exact maximum. This reading arose under mild southerly advection of warmer Atlantic air beneath a high-pressure ridge, paired with moderate solar insolation and partly cloudy skies that limited further warming. The Finnish Meteorological Institute's ensemble models had projected a peak near 18°C, with modest uncertainty in cloud timing explaining the tight clustering around 19°C. Historical May averages near 15°C place the outcome slightly above baseline, while the narrow 0.1% odds on 20°C or higher reflect the low likelihood of exceeding station thresholds once data finalized.