ARE YOU GOING TO SAN FRANCISCO? If the answer is yes then you will need to check the forecast before you leave.
San Francisco may be in California and we all know how wonderful the weather in California can be. But do not get caught out.  | | Golden Gate Bridge |
The West Coast climate is surprisingly cool. Or perhaps not so surprisingly when one remembers that the waters of the Pacific are much colder than the equivalent latitude across the Atlantic.
They are cold enough even in May to spot whales migrating northwards to the colder waters of the Arctic.
The warmest months are July, August and September. But even in the height of summer average temperatures are no better than 21 Celsius (73F), no more than 2 Celsius higher than, say, London. The proximity of such cold seas means that even in summer a sunny start to the morning is no guarantee for a fine day.  | | Many areas of the city are popular with tourists. |
Heating inland tends to draw cold air from the sea into the San Francisco Bay and across much of the City.
This cold air is often accompanied by low cloud and it is not uncommon for the Golden Gate Bridge to be covered in a shroud low cloud and the subject of a strong, cold wind. At the same time, the downtown area can be warm and sunny. Of course the winds do not always blow in off the sea.
Hot, dry winds blowing from the Mojave Desert or the San Juan Valley can result in exceptionally high temperatures.
From March through until October temperatures in excess of 30 Celsius (86F) have been recorded and a September record of 38 Celsius (101F) is fairly remarkable.  | | Alcatraz |
Whilst summer months can be somewhat extreme, the winters are characterised by pretty mild conditions.
Even in mid-winter temperatures rarely fall below 7 or 8 Celsius (43 to 46F). Freezing conditions are unusual and the lowest temperature ever recorded in the City was only Minus 3 Celsius (27F).
With a high frequency of fog, sunshine is not as high as a latitude of 37.5 degrees North would suggest. (San Francisco is on the same latitude as the Algarve.) Winter rainfall is certainly higher than either Bristol or London, but rainfall in summer and early autumn is extremely low. Almost any time of the year is a good time to visit San Francisco. Although December and January are quite cool and wet, the rest of the year offers the chance of some fine and sunny weather.
But if there was ever a destination for which checking the forecast beforehand was advisable, San Francisco is that destination. | 
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