Sarpsborg's winters are cold and dark, with temperatures often below freezing, averaging around 1°C in January and February. Spring arrives slowly, with March and April temperatures gradually warming up to an average of 5°C. Summer brings mild highs, with July being the warmest month, averaging 16°C, but nights can still be cool. Autumn is similar to spring, with temperatures gradually cooling down from September's average high of 13°C. Winters return in November and December, bringing cold temperatures once again, though not as extreme as January and February.