Lahti, Finland's climate is marked by cold winters with temperatures often dropping below -20°C, especially in January and February. Spring arrives slowly, with March temperatures gradually warming up towards average, while April brings mild days with occasional warmer highs. Summer months of June to August are warm, with July being the warmest month on record, but still relatively cool compared to other European cities. Autumn is a transition period, with September experiencing a slight drop in temperature and October returning to cooler conditions. Winters return by December, with temperatures similar to those in January.