Recent ensemble forecasts from the Finnish Meteorological Institute and ECMWF models indicate a likely daily maximum near 14–16°C at Helsinki-Vantaa on May 19, driven by a weak high-pressure ridge and moderate southwesterly flow. With leading market shares clustered tightly between 19–22°C, traders are pricing in substantial uncertainty from small differences in afternoon boundary-layer mixing, timing of thin high clouds, and local sea-breeze effects that can suppress or briefly enhance peak readings by 1–2°C. Historical May climatology shows a 15°C mean high, so current guidance sits slightly below average, yet model spread and the short two-day lead time keep outcomes from 18°C to 23°C all plausible until updated high-resolution runs and surface observations arrive tomorrow.