Clear skies and light northeasterly winds have enabled strong nocturnal radiative cooling over Madrid on September 10, 2026, driving overnight temperatures steadily downward from afternoon highs near 28°C. Multiple forecast models, including GFS runs and official guidance, converge on a minimum of 11–13°C during the pre-dawn hours, with dry air and minimal cloud cover supporting further drops below typical early-September averages of 15–16°C. This atmospheric setup explains the market’s near-certain pricing of 11°C or below. Only an unexpected increase in cloud cover or wind speeds before sunrise could limit cooling and push the observed low above the threshold.