Oulu's winters are harsh and cold, with temperatures often dropping below -20°C in January and February. Spring is a slow process, with March still quite chilly, but April brings a welcome warmth as temperatures rise above freezing. Summer months of June to August bring mild temperatures, rarely exceeding 30°C, while September marks the beginning of autumn's cool-down. October and November are characterised by crisp air and temperatures fluctuating around 0°C. Winter returns in December with sub-zero temperatures and occasional brief thaws.