Portsmouth's winter months are typically cold, with temperatures ranging from -6°C to 16°C in January and February, averaging around 4-5°C. As spring approaches, temperatures gradually warm up, reaching an average of 14°C by April and 18°C by May. Summer brings warmer days, with highs often above 30°C, but temperatures rarely drop below 10°C, peaking at an average of 25°C in July and August. Autumn sees a return to cooler temperatures, averaging around 9°C from September to December. Overall, Portsmouth's temperature fluctuations are relatively mild, with few extreme variations throughout the year.