Leszno's winters are cold, with temperatures often below freezing, but occasional warmer periods bring temperatures up to around 12°C in January. Spring is a slow warming process, with March and April temperatures gradually increasing towards the mid-teens. Summer brings warm days, with June and July temperatures frequently reaching highs of over 30°C, while August experiences a slight cooling trend. Autumn is mild, with September and October temperatures ranging from around 3-25°C, before dropping again in November. The coldest months are January and December, which often see temperatures below -17°C, while the warmest month is June.