**Trader sentiment strongly favors a 21°C high in Warsaw on September 28, 2026, at 95.5% implied probability.** Multiple forecast models, including GFS runs, converge on a clear, sunny day with high pressure near 1030 hPa, light southeast winds, and minimal cloud cover, supporting afternoon maxima of 19–21°C after morning lows around 8–11°C. Official observations and hourly guidance show steady warming under stable anticyclonic conditions, consistent with late-September climatology for the region. This positioning reflects aggregated trader assessment of real-time model consensus and surface observations. A realistic challenge would require unexpected persistent cloud build-up or a rapid wind shift suppressing insolation, though current stability makes such shifts improbable before resolution.