Dubuque's winters are harsh, with temperatures often plummeting below freezing and staying well into the negatives. Spring brings a slow warming trend, with temperatures gradually rising by April. Summer days can be warm, but highs rarely exceed 35°C, while autumn is characterized by mild temperatures that dip back down in November. The coldest months typically occur from December to February, while July and August are usually the warmest, with average temperatures hovering around 22°C.