Winters in Boulogne-sur-Mer are cool and occasionally chilly, with temperatures often below freezing in January and February. Spring brings a gradual warming trend, with March and April temperatures rising steadily into the mid-teens. Summers are mild and pleasant, with July being the warmest month, although daytime highs rarely exceed 28°C. Autumn is marked by a return to cooler temperatures, with October and November experiencing a gentle cooling trend. Throughout the year, nighttime lows often drop significantly below daytime highs, resulting in moderate temperature fluctuations.