Trader consensus overwhelmingly favors a lowest temperature of 2°C or below in Helsinki on September 15 due to a persistent influx of Arctic air and clear nocturnal conditions favoring strong radiative cooling. Official monitoring from the Finnish Meteorological Institute and aligned global forecast models show overnight minima aligning with this threshold, consistent with the historical record low of 1.6°C for the date. This skin-in-the-game positioning reflects verified observational trends and model agreement rather than typical mid-September averages near 9°C. Resolution hinges on the official daily minimum reported by local stations; any unexpected warming from shifting winds or increased cloud cover could alter the final reading before close.