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Weather Overview for San Francisco

San Francisco has an incredibly varied climate due to its size and diverse topography. Generally, it has a very mild climate often described as Mediterranean, though it is much cooler than Mediterranean towns and cities. Warm temperatures extend San Francisco’s summer months though fog and cold winds are what the area is known for. Winters are rainy and mild to cold. The area is highly susceptible to earthquakes. The city sits on the west coast of the USA in the state of California.

Summer, from June till October, is warm but often foggy in later months. The average high temperature rises to 19°C in June, to a peak of 23°C in July then very gradually decreases, getting down to a still pleasant 20°C in October. Night times are much cooler and sometimes cold. While fog can set in at any time it is more frequent towards the end of the season. Fog brings with it cold temperatures and reduced visibility. June sees a delightful eleven hours of sunshine; this slowly decreases throughout the season but by October eight hours per day can still be expected. These hours are usually spread amongst long periods of constant sunshine and days of inescapable grey or fog. Rainfall is very low but the end of the season sees a few showers. The sea never gets above 14°C.

Autumn to spring, from November till May, is cool with little variation. The warmth of summer quickly falls away, getting down to 17°C in November, 14°C in December and its lowest of 13°C in January. Night times stay under 10°C; it rarely gets down to freezing in coastal regions but frost has been known at higher elevations. Sunshine reduces and rainfall increases; fog and drizzle are common. January is the wettest and coldest month. It is still much sunnier than many other parts of the world at this time of year. In its least sunny month, December five hours per day can still be expected while Berlin can hope for around one hour per day.

It is generally warmer in the west in comparison to the east due to proximity to the continent and the cooling west winds which are blocked by high land in the middle of the peninsula. It is also foggier on the Pacific coast than in the eastern bay side. San Francisco’s climate is modified greatly by the cool waters of the Pacific Ocean which surrounds the city on three sides due to its position on a peninsula. Northwest winds and ocean currents cool the city in the summer but keep it mild in the winter. The cool sea and hot regions in inland California combine to create the characteristic fog of the city.