Lappeenranta's winters are harsh and cold, with temperatures often dropping below -20°C and averaging around -6°C in January. Spring brings gradual warming, with temperatures rising to above freezing by April, averaging around 4°C. Summer is mild, with average highs of around 21°C in July, although occasional heatwaves can push temperatures into the mid-30s. Autumn sees a return to cooler temperatures, with averages dropping back down to around 1°C by November. The coldest months are January and December, while June and July are usually the warmest.