**Recent forecasts for Helsinki on September 13, 2026, show overnight lows clustering near 6–11°C, creating closely matched market probabilities around 28–29.5% for the top outcomes (11°C, 6°C or below, 16°C or higher).** This tight distribution reflects genuine forecast uncertainty in short-range numerical weather prediction models. The minimum temperature, which typically occurs just before sunrise around 06:15 local time, depends primarily on radiative cooling under clear or partly cloudy skies, light winds, and dew point depression. Current guidance from sources like the Finnish Meteorological Institute, Met Office, and others indicates a daytime high near 15–17°C with a nocturnal drop to roughly 6–10°C, consistent with September climatology (average low ~9.7°C). Variable factors such as cloud cover timing, wind speed (currently light at 2–7 m/s), and any residual moisture from light showers can shift the low by several degrees. Stronger radiative cooling under clearer skies could push readings toward or below 6°C, while increased cloudiness or mixing would favor values near 10–12°C. Higher minima (16°C+) remain possible only with unusually strong warm advection or persistent low cloud, which current runs do not strongly support. Traders are therefore pricing in the range of plausible model solutions rather than a single consensus value.