Winter in Chartres is cold and unpredictable, with temperatures often dropping below freezing in January and February. Spring brings a gradual warming trend, with March and April averaging around 7-8°C, marking the beginning of milder days. Summer is warm to hot, with June and July being the warmest months, sometimes reaching highs above 30°C, while August can be slightly cooler. Autumn is mild, with temperatures gradually cooling down in September and October, before a brief chill in November and December.