San Francisco is renowned for its cold, foggy summers. However, when September and October come around, the character lovingly known as Karl the Fog recedes, and temperatures can climb into the low 80s on the hottest days. Late winter can see some rain, but rarely much. Overall, the unique geography of this peninsula, bound as it is by the Bay and the Pacific, creates pockets of both warm and cool weather all year long. Dress in layers, and be prepared to encounter a range of temperatures as you make your way around the city.