Short-range ensemble forecasts from models such as ECMWF and GFS place the highest temperature in Helsinki on August 5 near 20–22°C, producing the tightly matched market-implied odds. This narrow distribution arises from modest differences in projected cloud cover, which modulates incoming solar radiation, and the precise trajectory of a weak high-pressure ridge steering air masses over the Baltic Sea. Southerly flow could add a degree or two through warm advection, while increased low-level moisture or lingering frontal cloud would cap daytime maxima closer to 20°C. Official guidance from the Finnish Meteorological Institute will update rapidly in the next 48 hours, tightening the spread as observational data refine boundary-layer conditions and any diurnal heating peaks.