Forecast models from the ECMWF and GFS show genuine uncertainty for Amsterdam’s minimum temperature on September 26, keeping the 8 °C-or-below and 18 °C-or-higher outcomes nearly tied. A lingering Atlantic low-pressure system could deliver northwesterly flow of cooler maritime air and clearer skies that enhance overnight radiative cooling, while a stronger high-pressure ridge would favor milder southerly winds and increased cloud cover that limits heat loss. Historical late-September averages near 11–13 °C provide little guidance given current model spread. Traders will watch the next KNMI and ECMWF runs for shifts in 2-meter temperature guidance and wind-vector consensus before the market resolves.