Recent model consensus from European and global ensembles points to a mild, rainy day in Helsinki driven by southerly flow and building high pressure, with daytime maxima near 14–16 °C but nocturnal minima highly sensitive to cloud cover and rain timing. Persistent overcast and showers limit radiative cooling, favoring minimums around 11–13 °C, while any clearing or stronger northerly advection could drop readings toward single digits. Conversely, delayed frontal passage or warmer maritime air could push lows above 15 °C. This genuine forecast spread—typical for late-September Baltic transitions—explains the near-even market-implied odds between sub-7 °C and 16 °C-plus outcomes, with traders weighting the latest ECMWF and GFS runs ahead of the 26 September resolution window.