 Low-lying inland valleys, especially the Central Valley, have a hot-summer Mediterranean climate (Köppen "Csa"), with subtropical temperatures but a well-defined summer dry season and a foggy, rainy season in winter.The temperature gradient between immediate coast and low-lying inland valleys in the south is about 7 °F (4 °C) in winter, the coast being warmer, and in summer roughly 25 °F (14 °C), the interior being warmer.For example, the average daily high in San Francisco in July and August is between , and in Walnut Creek, some inland, the average daily high in July and August is