Cagliari has a hot-summer Mediterranean climate , with hot, dry summers and mild winters like other historical regions along the coast. Its precipitation values also bring it closer to semi-arid conditions. The summer extreme values can be slightly over 40 °C (104 °F), sometimes with very high humidity, while in winter, under special and rare conditions, the temperature drops slightly below zero. Heavy snowfalls occur on average every thirty years.
The average temperature of the coldest month, January, is about 10 °C (50 °F), and of the warmest month, August, about 25 °C (77 °F). But heat waves can occur, due to African anticyclone, starting in June. From mid-June to mid-September, rain is a rare event, limited to brief afternoon storms. The rainy season starts in September, and the first cold days come in December.
Winds are frequent, especially the mistral and sirocco; in summer a marine sirocco breeze (called s’imbattu in Sardinian language) lowers the temperature and brings some relief from the heat.