Incoming Atlantic low-pressure systems and associated cloud cover are the dominant short-term drivers keeping trader-implied odds clustered around 9–14 °C for Moscow’s overnight minimum on 21 August. Ensemble forecasts from the European Centre for Medium-Range Weather Forecasts and Roshydromet show modest advection of cooler maritime air combined with variable nocturnal cloudiness that limits radiative cooling, producing a narrow range of expected lows near the late-August climatological average of 12–14 °C. Clear-sky scenarios would allow stronger surface heat loss and push readings toward or below 9 °C, while increased low-level moisture or wind mixing would hold minima near 13–14 °C. With probabilities tightly bunched, any updated 00–12 UTC model runs or observed dew-point trends before resolution will likely shift the tight 33–39 % bands among these outcomes.