possible night frosts. These occur few times during winter, with temperatures generally not falling below because of the oceanic influence that moderates the temperature; a few kilometres inland, frosts are more common and colder. On the other hand, even in the middle of winter it's not uncommon to have temperatures above for a few days. Rainfall and sleet are a frequent winter occurrence, but snowfall is extremely rare: flurries have been recorded only four times but with no accumulation, the last one on 13 July 1930 during the inaugural match of the World Cup, (the other three snowfalls were in 1850, 1853 and 1917); the alleged 1980 Carrasco snowfall was actually a hailstorm. Summers are warm-hot and humid, with less wind than other seasons. The average temperature in this season is . Daytime temperatures are usually between and , while night lows between and . During this season, a moderate wind often blows from the sea in the evenings which has a pleasant cooling effect on the city, in contrast to the more severe summer heat of nearby cities like Buenos Aires. Heat waves come with the north winds, which bring humid and hot air masses from the tropical interior of the continent; temperatures can rise above . These warm periods are usually followed by thunderstorms, generated by cold fronts from the southwest that lowers temperatures considerably. This phenomenon is regional, and can occur several times all year long. The autumn in Montevideo is quite pleasant and not so unstable. Daytime temperatures are in general around and nights around . Spring average temperatures are very similar to the autumn, but the weather in that season tends to be more windy and volatile, with more dramatic changes in a short period of time. Montevideo has an annual average temperature of . The lowest recorded temperature is while the highest is . Administrative divisions and barrios , the city of Montevideo has been divided into 8 political municipalities (Municipios), referred to with the letters from A to G, including CH, each presided over by a mayor elected by the citizens registered in the constituency. This division, according to the Municipality of Montevideo, "aims to advance political and administrative decentralization in the department of Montevideo, with the aim of deepening the democratic participation of citizens in governance." The head of each Municipio is called an alcalde or (if female) alcaldesa. Of much greater