Recent ensemble forecasts from European and global models point to a minimum temperature in Helsinki on September 20 most likely falling between 9–11 °C, reflecting a mild southerly flow ahead of an approaching Atlantic front. Light winds, increasing cloud cover, and scattered showers overnight are expected to limit radiative cooling, keeping the low above the seasonal climatological mean of roughly 8–9 °C. Model spread in the exact timing and intensity of the frontal passage creates the tight clustering of market-implied probabilities around 8–11 °C, while the small tails on colder or warmer outcomes capture residual uncertainty in boundary-layer mixing and precipitation timing. Updated runs from the Finnish Meteorological Institute and ECMWF over the next 24–48 hours will provide the key data traders are watching.