Hanoi features a monsoon-influenced humid subtropical climate (Köppen ''Cwa'') with plentiful precipitation. The city experiences the typical climate of northern Vietnam, with four distinct seasons. Summer, from May to August, is characterized by hot and humid weather with abundant rainfall, and few dry days. Hot, dry conditions caused by westerly winds during summer are rare. From September to November comprise the fall season, characterized by a decrease in temperature and precipitation. Winters, from December to January, are characterized as being mild with large amounts of drizzle and little sunshine. The city is usually cloudy and foggy in winter, averaging only 1.5 hours of sunshine per day in February and March.