**Mild Atlantic airflow, persistent cloud cover, and overnight rain are keeping Helsinki temperatures elevated on August 30, 2026, positioning 15°C as the market favorite (62% implied probability) while supporting a secondary cluster around 13°C.** Official forecasts from the Finnish Meteorological Institute and models such as ECMWF/GFS show daytime highs reaching 18–19°C under mostly cloudy skies with southerly winds of 10–15 mph and scattered showers. These conditions limit radiative cooling, with dew points near 16–17°C and high humidity (85–95%) preventing the temperature from dropping sharply after sunset. Overnight lows are consistently projected near 15–16°C (roughly 59–61°F), consistent with the dominant 15°C outcome. Historical averages for the date are lower (~11.9°C), but the current warm anomaly—driven by a stable mild air mass rather than any strong cold advection—explains why probabilities for 13°C remain substantial (44.5%) while colder outcomes (≤12°C) sit below 5%. No major forecast revisions have occurred in the past 24–48 hours; the primary catalyst remains the ongoing cloudy, moist pattern that favors a minimum near 15°C. Traders are therefore pricing the resolution threshold around the consensus model guidance for the overnight period.