Montreuil's winters are cool and variable, with temperatures often dropping below freezing in January and February, but occasionally rising into the mid-teens. As spring arrives in March and April, temperatures gradually warm up, reaching averages of around 8°C, with occasional highs above 25°C. Summer is mild to warm, with July and August averaging around 19°C, while June can be quite pleasant with average highs often reaching over 30°C. Autumn brings a return to cooler temperatures, with September and October experiencing temperatures ranging from 3-23°C, before the winter chill sets in again by November and December.