Lille's winters are cold and variable, with temperatures often below freezing in January and February, but occasionally rising above average. As spring approaches, temperatures gradually warm up, with March and April experiencing mild days and cooler nights. Summers are generally pleasant, with June and July averaging around 17°C, while September sees a slight drop in temperature before the onset of autumn. Autumn is characterized by cool mornings and warmer afternoons, with October being the mildest month of the season. Winters return in December, bringing chilly temperatures that are not as extreme as those in January and February.