**Forecast uncertainty around an incoming weather system is driving the tightly bunched market prices around 20–22 °C for Warsaw’s August 29 maximum temperature.** Official and ensemble guidance show a transition from clear, anticyclonic conditions (today’s highs near 25 °C under easterly flow) to increasing southwesterly winds, cloud cover, and showers or rain on the 29th as a low-pressure trough approaches. This reduces daytime insolation and evaporative cooling, keeping the daily maximum in a narrow 20–24 °C window across most model runs. Differences among the leading outcomes hinge on small variations in forecast details: the exact timing and coverage of precipitation (which can suppress temperatures by 1–3 °C), the degree of low-level cloudiness limiting solar heating, and the strength of the southerly advection of milder air. Historical late-August climatology for Warsaw centers near 21–22 °C, providing a baseline that current guidance largely tracks. With resolution only two days away and new model cycles expected overnight, traders are assigning the highest implied probabilities to the middle of the plausible range while leaving room for modest shifts if the rain arrives earlier or later than currently projected.