Madrid and its metropolitan area has a Mediterranean climate (Köppen climate classification: Csa) which transitions to a cold semi-arid climate (BSk). According to the Troll-Paffen climate classification, Madrid has warm-temperate subtropical climate (Warmgemäßigt-subtropisches Zonenklima) and according to the Siegmund/Frankenberg climate classification, Madrid has a subtropical climate. However, the most widespread climate classification is that Madrid presents a climate of transition between the Mediterranean climate (Köppen climate classification: Csa) and the cold semi-arid climate (BSk), with hot summers and relatively cool winters with somewhat frequent frosts (15 days have lows under 0 °C (32 °F) on average) and occasional snowfalls, with 3-4 snowy days on average.