Poznan's climate is characterized by cold winters with occasional thaws, as seen in the wide temperature ranges during January and December. Spring brings gradual warming, with March temperatures averaging around 4°C, while April and May see a steady increase to average highs of 6°C and 12°C respectively. Summer months are warm but not hot, with July being the warmest at an average high of 21°C. Autumn is mild, with September averaging around 15°C, before cooling down in October and November. The temperature fluctuations between day and night are significant throughout the year, with cold nights common even during warmer months.