Winters in Jonkoping are cold and dark, with temperatures often below freezing, averaging around -3°C in January and December. Spring brings a slow warming trend, with temperatures slowly rising above freezing by April, but still quite variable. Summer is mild to warm, with highs occasionally reaching 30°C in June and July, but more typically ranging from 15-25°C. Autumn is similar to spring, with temperatures cooling gradually over the course of September and October. The coldest months are January and December, while the warmest months are June and July.